SSRS 2019 Reports are painfully slow to display - despite nil retrieval, processing, and rendering times

I'm migrating an SSRS implementation from a SQL Server 2012 to SQL Server 2019 server, and the reports run painfully slow on 2019. We're talking minutes. Even just getting to the parameter screen can take 30-40 seconds even if those parameters don't pull dynamic data.

I've scoured the internet and while it seems like this is a common question, the answers point toward making the DB queries more efficient, using Stored Procedures, turning off CEIP... but I'm finding the report takes minutes even when the report doesn't pull any data from SQL Databases.

I created a Test report that has a single text field parameter, and the dataset is literally just:

SELECT
 * FROM
 (VALUES ('test 1', 'test 2', 'test 3')) E(test,test2,test3)

When I first click the icon to load the report, it takes 25 seconds just to load the parameter screen. When I click "View report" it takes about 45 seconds to display the report. The report is simple and obviously isn't a database query inefficiency issue.

When I run a query against ExecutionLog3 for this report, the TimeDataRetrieval is usually 0.003 seconds, the Time processing between 0.007 and 0.03 seconds, and TimeRendering from 0.003 and 0.3 seconds. But the Duration between TimeStart and TimeEnd is anywhere from 45 seconds to 1:09!

Any ideas or suggestions as to why SSRS is so slow on my new server, and where the rest of that time is coming from? I've also watched the performance stats on the server and cpu and memory are not stressed in the least.

Thanks for your help.

What ended up being the solution here... was just reinstalling Reporting Services. :-/