Using ChickenChunks-1.16.5-2.9.0.87-universal.jar. Tried with a personal mod pack and just this mod. Place a chunk loader and click the + / - buttons to change the size of the loaded chunks. The numbers don't change and the actual chunk loading size does not change.

Same here; additionally, it seems like you can't change the shape of the lasers either (it's stuck on square).

I have this same issue. Running Minecraft version 1.16.5 forge 36.2.9 on Ubuntu 20.04.

This issue has now been resolved.