Thanks for the awesome mod. I have been having two issues that I suspect may be related. First, occasionally the glass doesn't actually place, or for some reason turns invisible. It makes a placing sound, but is not visible. I suspect this may be related to the vertical slabs mod that I am using, but I don't know for sure. Also, when breaking the glass, it sometimes crashes the game. I suspect it may be when breaking the glass on top of the vertical slabs or perhaps when the glass overlaps with one of the failed placements. Regardless, I have attached a github link that has the crash report. Thanks for your time.

Crash Report

As a note: The occasional issue where a PITG pane doesn't place correctly has been addressed in the latest release. It was related to other mods not honoring the block states if they override the PITG block placing mechanics. PITG always assumed that panes would only have valid block state combinations and would not render the invalid ones. This has been changed to use a default valid state for any invalid combinations.

I blame Waddles (just kidding, kind of)
Waddles has had a history of causing unusual issues in other mods

Looking at your mod list, is Decorative Blocks the vertical slab mod you are referring to? I'm trying to reproduce the problem and I want to make sure I'm looking at the right mods

The mod is called double slabs, it allows you to place two slabs of different types in the same block as well as place them vertically.