gob.Register name not registered for interface in another package

I have recently restructured my code so that now under the main package there are two packages: chain and api.

In chain I defined a few structs SomeStruct1, SomeStruct2 and an interface SomeInterface for those structs. The following is what chain/cli.go looks like.

package chain

type CLI struct{}

func (cli *CLI) Run() {
    ...
    gob.Register(SomeStruct1{})
    gob.Register(SomeStruct2{})
    ...
}

There is another similar api/api.go where inside Run() I put gob.Register(chain.SomeStruct1{}).

main.go looks like this:

package main

import (
    "myproj/api"
    "myproj/chain"
)

func main() {
    // I have also tried the following lines.
    // gob.Register(chain.SomeStruct1{})
    // gob.Register(chain.SomeStruct2{})
    go api.Run()

    cli := chain.CLI{}
    cli.Run()
}

However, I got the error gob: name not registered for interface: "main.SomeStruct1" at runtime. This did not happen when I had all the code inside one main package and I felt weird that SomeStruct1 is now under chain package but the error referred to main.SomeStruct1. Where did I get wrong of gob.Register()?

I have not been able to solve the problem completely and I think the cause was that chain.SomeStruct1 was somehow recognized at runtime as having the name main.SomeStruct1 while it was registered with the internal name main.SomeStruct1.

Therefore a workaround I have now is using gob.RegisterName("main.SomeStruct1", chain.SomeStruct1).