[SOLVED] Proxysql Isn't sending data to MySQL replicas/slaves in a multi db cluster

TLDR; Proxysql isn't sending any data to or replicas. The master works just fine, and the replicas are all caught up, but they aren't serving traffic.

Overview: The main issue is that no traffic is going to the replicas:

We have 4 mysql clusters. Each one has a master, and two replicas.
The replicas are all caught up to master and replicating fine.
We are on... Drupal (sigh) for now, so we have multiple databases per cluster. All with their own proxysql user and default host group.
Proxysql shows null on connection errors to the replicas. It looks like it can connect.
But all the traffic just hits the master. It serves all select, update, and delete statement.
We have our masters and replicas set up in their own write and read groups (not in the same host group as we'd prefer to manually dictate which is a master and which are replicas).

Question: How do we get data hitting our replicas and not just the master?

Configs:

mysql_users=
(
{ username = "company1", password = "aaaaaabbbbbbccccccdddddddfffffff", default_hostgroup = 10, max_connections = 200, active = 1, transaction_persistent = 0 },
{ username = "company2", password = "aaaaaabbbbbbccccccdddddddggggggg", default_hostgroup = 10, max_connections = 200, active = 1, transaction_persistent = 0 },
{ username = "company3", password = "aaaaaabbbbbbccccccdddddddhhhhhhh", default_hostgroup = 20, max_connections = 200, active = 1, transaction_persistent = 0 },
{ username = "company4", password = "aaaaaabbbbbbccccccdddddddiiiiiii", default_hostgroup = 20, max_connections = 200, active = 1, transaction_persistent = 0 }
.... and lots more. 
)

mysql_servers =
(
# Cluster 1 (Master|Write Hostgroup)
{ address = "10.0.0.1", port  = 3306, hostgroup = 10, status = "ONLINE", weight = 1000, compression = 0, max_replication_lag = 2, max_connections = 300, max_latency_ms = 2000, comment="Cluster 1 (Master DB-1)" },
# Cluster 1 (Slave|Read Hostgroup)
{ address = "10.0.0.2", port  = 3306, hostgroup = 11, status = "ONLINE", weight = 1000, compression = 0, max_replication_lag = 2, max_connections = 300, max_latency_ms = 2000, comment="Cluster 1 (Slave DB-2)" },
{ address = "10.0.0.3", port  = 3306, hostgroup = 11, status = "ONLINE", weight = 1000, compression = 0, max_replication_lag = 2, max_connections = 300, max_latency_ms = 2000, comment="Cluster 1 (Slave DB-3)" },

# Cluster 2 (Master|Write Hostgroup)
{ address = "10.0.0.4", port  = 3306, hostgroup = 20, status = "ONLINE", weight = 1000, compression = 0, max_replication_lag = 2, max_connections = 300, max_latency_ms = 2000, comment="Cluster 2 (Master DB-4)" },  
# Cluster 2 (Slave|Read Hostgroup)
{ address = "10.0.0.5", port  = 3306, hostgroup = 21, status = "ONLINE", weight = 1000, compression = 0, max_replication_lag = 2, max_connections = 300, max_latency_ms = 2000, comment="Cluster 2 (Slave DB-5)" },
{ address = "10.0.0.6", port  = 3306, hostgroup = 21, status = "ONLINE", weight = 1000, compression = 0, max_replication_lag = 2, max_connections = 300, max_latency_ms = 2000, comment="Cluster 2 (Slave DB-6)" },
)

mysql_replication_hostgroups=
(
# Cluster 1
{ writer_hostgroup=10, reader_hostgroup=11, comment="Cluster 1 Master / Slave 1 " },
# Cluster 2 
{ writer_hostgroup=20, reader_hostgroup=21, comment="Cluster 2 Master / Slave 1" },
)

mysql_query_rules=
(
  { rule_id = 1, active = 0, match_digest = ".", log = 1, apply = 0 },
  { rule_id = 2, active = 1, match_digest = "^SELECT\sname,\stype\sfrom\ssystem\sWHERE\sstatus.*", cache_ttl = 3600000, flagOUT = 2, apply = 1 },
  { rule_id = 3, active = 1, match_digest = "SELECT\sDISTINCT\sregistry.name\sAS\sname,\sregistry.filename\sAS\sfilename\sFROM\sregistry.*", cache_ttl = 3600000, flagOUT = 2, apply = 1 },
  { rule_id = 4, active = 1, match_digest = "SELECT\s.*\sFROM\smenu_router\sWHERE\spath\sIN.*", cache_ttl = 3600000, flagOUT = 2, apply = 1 },
  { rule_id = 5, active = 1, match_digest = "SELECT\sbase.vid\sAS\svid,\sbase.name\sAS\sname,\sbase.machine_name\sAS\smachine_name,\sbase.description\sAS\sdescription,\sbase.hierarchy\sAS\shierarchy,\sbase.module\sAS\smodule,\sbase.weight\sAS\sweight\sFROM\staxonomy_vocabulary\sbase\sWHERE", cache_ttl = 300000, flagOUT = 2, apply = 1 },
  { rule_id = 6, active = 1, match_digest = "^SELECT\snid,\sdata\sFROM\scompany_sync_nodes", flagOUT = 2, apply = 1 },
  { rule_id = 7, active = 1, match_digest = "^SELECT\sclient_name_display\sFROM\siss_dispatch_clients", flagOUT = 2, apply = 1 },
  { rule_id = 8, active = 1, match_digest = "SELECT\sf.fid\sAS\sfid\sFROM\sfile_managed\sf\sWHERE\s(f.status\s=\s.*)\sAND\s(f.uri\sLIKE\s.*\sESCAPE\s.*)\sAND\s(f.uri\sNOT\sLIKE\s.*\sESCAPE\s.*)\sAND\s(f.filemime\sNOT\sLIKE\s.*\sESCAPE\s.*\sORDER\sBY\sf.fid\sDESC\sLIMIT\s.*\sOFFSET\s.*", flagOUT = 2, apply = 1 },
  { rule_id = 9, active = 1, digest = "0x6C21FFE9B05A6873", flagOUT = 2, apply = 1 },
  { rule_id = 10, active = 1, digest = "0x6C21FFE9B05A6873", flagOUT = 2, apply = 1 },
  { rule_id = 11, active = 1, digest = "0x7E8E89B6752B147F", flagOUT = 2, apply = 1 },
  { rule_id = 12, active = 1, digest = "0xF41E2E690383C416", flagOUT = 2, apply = 1 },
  { rule_id = 13, active = 1, match_pattern = ".*ProxySQLSendToSlave.*", flagOUT = 2, apply = 1 },
  { rule_id = 99, active = 1, match_digest = ".", flagOUT = 1, apply = 1 }
)

mysql_variables=
{
  threads=4
  max_connections=2048
  connection_max_age_ms=1200000
  max_transaction_idle_time=1200000
  monitor_replication_lag_count=3
  default_query_delay=0
  default_query_timeout=36000000
  have_compress=true
  poll_timeout=2000
  interfaces="0.0.0.0:6033"
  default_schema="information_schema"
  stacksize=1048576
  server_version="5.5.30"
  connect_timeout_server=3000
  monitor_username="myusername"
  monitor_password="mypassword"
  monitor_history=600000
  monitor_connect_interval=30000
  monitor_slave_lag_when_null=60
  monitor_replication_lag_interval=30000
  monitor_ping_interval=10000
  monitor_read_only_interval=1500
  monitor_read_only_timeout=500
  ping_interval_server_msec=120000
  ping_timeout_server=500
  commands_stats=true
  sessions_sort=true
  connect_retries_on_failure=10
  monitor_writer_is_also_reader=false
  eventslog_filename="queries.log"
  log_unhealthy_connections="false"
  query_cache_size_MB=2000
}