Forge timed spawn confusion

How do you make a weapon spawn after a set time?
I can get vehicles, armour abilities and fusion coils to spawn after a set time, but weapons just don’t work.
I set the weapon to not spawn at start and spawn after 20 seconds but it never spawns.
Does anyone know if there are certain gametype rules to change?

I never had this problem but sometimes if you’re holding that specific weapon, it won’t spawn. That’s how it is in Matchmaking, so I’m assuming the same rules apply.

The gametype has players start off with pistols and I want rockets to spawn.
I downloaded another gametype that has a weapon spawn in but I can’t work out what the creator did to make it work.