Hi,
The light overlay is not showing up on a vanilla server. Since the mod is client-side, I am under the impression that it should work okay. I am running the latest JRE. The little status thing that says "light overlay" appears in the top left corner (as I think it probably should), and I can toggle it with F7, but nothing shows up. It works as expected in singleplayer.

Update architectury, plus, your room is well lit so there aren't any crosses.

Apologies- I apparently misunderstood how the mod worked. I walked in here just to take the screenshot, though. It looks to be working as expected.

Thank you, sorry for the misfire.

No worries, enjoy the mod!