Current questions and answers regarding the map editor.

So, is there something else I haven't done?

I think so.
The hero's army shouldn't affect it. Most often, the problem is the absence of a castle or enemies, something like that...

Hello! Can you tell me how to change or add a custom starting bonus on a map (not a campaign), besides the three that already exist?

Like gold/resources/artifact/something else? I'm afraid that it's not possible, or it requires a rather complex mod.
You can add additional effects to the bonuses using scripts, but without a mod, it won't be displayed in the interface when selecting a map.