I couldn't find anyone else reporting this bug so I opened a ticket here...
Basically, in the last MCreator version (2020.1), when trying to load a modded dimension, it freezes. It looks like it can't generate the chunks.
The bug appears while accessing any dimension from any workspace (both RaolCraft and Hodge-Podge have the same issue).
Here is the log if you need it: https://pastebin.com/vfd9BcAn
If you can't replicate it I can send you the workspaces.
(I also found another bug regarding GUIs but I will report it later)
Issue comments
Thank you for replying, I think it was the same bug causing GUIs to no work (so you fixed two issues in one XD)
By the way, I found a little bug regarding advancements: you can remove their "grant this advancement to the player" block, which can then no longer be added back
You are welcome!
Anyway, are the new advancement triggers (the ones you define in the advancement mod element) only supposed to be used with 1.14? Because I tried using the "if player enters dimension" trigger but it caused crash when creating a world
Triggers should work on 1.12.2 too, but not all of them might be supported.
Without workspace I can guess based on this:
that you did not reselect advancements when updating to 2020.2.
From the changelog: