This seems to be an anomaly only when Antique atlas is in my current mod pack.
This was an issue when the server first started about 4 months ago and has returned with the introduction of Antique Atlas once more which is needed for another mod to work properly.
This happens across multiple versions of Forge (about 5 tested versions including the most recent).
The moment Antique atlas is removed the missing textures and incorrect textures return to normal.
This seems to be an anomaly only when Antique atlas is in my current mod pack. This was an issue when the server first started about 4 months ago and has returned with the introduction of Antique Atlas once more which is needed for another mod to work properly. This happens across multiple versions of Forge (about 5 tested versions including the most recent).
The moment Antique atlas is removed the missing textures and incorrect textures return to normal.