• ctp_1.2_MCv3
  -CTM-MC1.12-0.2.3.9

Optifine is NOT installed.

Oh closed it because because it was previously reported on the ctm mod tracker

Is it safe to assume this won't be fixed or doesn't have a fix action being worked on?

They will be fixed next update 1dd8996

Thank you for the update!

Erm, any chance an update could be pushed? I don't want to be "that guy"

If you're still looking for a simple solution @Alaberti, you can just copy the pane_side.json and pane_side_alt.json from the minecraft/models/block folder into your ressource pack and proceed the following modifications :

• In pane_side.json : "west": { "uv": [ 16, 0, 9, 16 ], "texture": "#pane" },
  become "west": { "uv": [ 0, 0, 7, 16 ], "texture": "#pane" },
• In pane_side_alt.json : "west": { "uv": [ 7, 0, 0, 16 ], "texture": "#pane" },
  become "west": { "uv": [ 9, 0, 16, 16 ], "texture": "#pane" },

The only remaining problems are the edges inside a tall window (pack improvement feature) and the disconnected textures between panes which make corners and those who are straight (bug in the mod : issue reported here)