When Minecraft tries to run both of these mods at the same time, something in the Fabric Seasons mod prevents Ultra Amplified Dimension from being able to create its "ultra_amplified_dimension" folder in the associated world folder's "dimensions" folder. I have found no other issues with this mod and a plethora of other mods though, with this exception.

Can you explain more of what the issue is? Can you access the dimension at all in-game and does it function?

Log with both mods on: https://paste.ee/p/y7RWZ

Looks like this is related to this issue report. Some of my surfacebuilders for biomes uses ice and snow blocks so by Seasons adding a new property to it, it blows up those surfacebuilders which in turn, blows up the biomes, which then blows up the entire dimensions oof.
lucaargolo/fabric-seasons#18

Keep watch on that issue report. Once they fix that, our mods should work together again.

Seasons has been updated to fix this issue! Try updating seasons and see if the issue is resolved