Summary: When you change the material of a frame shape block, you can't pick it up anymore if your inventory is full, even if the material of the frame placed and the one you have in your inventory is using the same material.
Platform: Windows 10
Game mode: SP
Repro steps:
1 - Go into dm and cm.
2 - Take some frame shape blocks from cm.
3 - Select 'material' from the radial menu while holding the frame shape block and pick any material.
4 - Place one frame shape and pick it back up.
5 - Pick random items from cm and make your inventory and toolbelt full.
6 - Place a frame shape down again, and confirm that you get a message saying that your inventory is full, even if the stack of frame shapes you have isn't full.
YT link: