My Colony Version 0.76.0 on Windows 10 via Ape Apps Launcher
I purchased a large quantity of materials from the GBT (50m steel, 6m gold, 5m uranium,
43k ancient instructions, and a few million of other resources.)

After posting the trades, and after receiving the resources I saved.

After loading the save a day later all these resources were gone, and my last purchase (3m clay came through.)

After accepting the clay I saved, and reloaded the game again. They disappeared as well.

When I saved I had the resources. When I loaded I didn't.