Topic category: Troubleshooting, bugs, and solutions
I can't create a new ticket, so I post the bug here.
MCreator: 2020.3 (16610)
Generator: Forge for Minecraft 1.15.2
Ok, so create two custom dimensions, and two advancements. In each advancement, choose the trigger "If player enter in dimension", and select the first dimension, and in the second advancement, the second dimension. Start the game (in 1.15.2), go inside one of the dimension, and you get the two advancements. I don't know why it happens because the code is the same with the two Forge generators.
I send you a workspace on Discord as I can't attach files.