PC 0.1.1.2193 Rel
Game Pass subscription
Was full inventory, 30 of 30. Dropped a Plant Fiber that was a single item in a slot, ui states 29 of 30. Go to pick up other items and told Inventory Full.
Picked up another item I didn't have a full stack of, Sap. Once that stack was full I could not pick up more despite the free slot.
Only unloading some items to a storage chest resolved the issue.
Didn't help:
Manually rearranging some items in inventory.
The redistribute button in inventory, can't remember the exact term. Stacks were optimized but still told Inventory Full.
Saving, quitting, and reloading the save.