With this mod is installed blocks affected by this mod (Dark Oak Door) don't load their textures properly until resource packs are reloaded (F3+T). This has to be done once per client launch.

Before

After

No errors appear in the log.

This didn't happen in my forge environment when using MoreWaterlogging as a dependency, but once I was running it inside a modpack the behaviour started. Disabling Morewaterlogging fixes the issue.

Issue has been reported on the CF comments previously. https://www.curseforge.com/minecraft/mc-mods/more-waterlogging?comment=39

I checked a variety of different mods to see if it was a conflict but couldn't find anything.
Checked:
CTM, Chisel, Quark.

This is a fun one because I never did find out which mod causes it.