Version Info

• Minecraft 1.21.8
• connectedglass-1.1.14-neoforge-mc1.21.6.jar

Steps to Reproduce
Place one single connecting glass pane
tested with clear glass and connecting glass (the block, not the pane) as well. No problems there. only the pane

Crash report
2025-08-14_21-45-57.log

I cannot reproduce the issue with just Connected Glass and dependencies installed.
I am not completely sure what the cause is, but I think it might be the issue I fixed in Fusion 1.2.11 which was related to Puzzles Lib which you do have installed.
Could you check if the issue persists with Fusion 1.2.11? If it does persist, could you narrow down the mods needed to reproduce the issue?