Certain decorative blocks from other mods cannot be used to mount hanging lights, for example, the Wooden Post and Wooden Wallmount from Immersive Engineering, Which is a shame, because they would look great with light garlands hanging from them. (Incandescent Lights work by themselves, at least.)

Version 1.16.4
Forge version 35.1.36

Thanks for the suggestion! I'll see what I can do.