I have found a way to get rid of this at the sacrifice of some of your gear:
- Start by dropping your backpack somewhere hidden that you know (make note of the server first so you can come back later and get it). It will not show up on the ground, you will have to quit and re-join the same server to 'refresh' your inventory.
- Leave the area, run at least 1000ft away.
- Exit and re-join the server. If the issue is fixed now, it was caused by an item in your backpack. You can now return to your backpack, pick it up and try to just drop one item at a time.
- Continue dropping items and leaving the area until you either found the item causing the issue, or have enough of your items to be happy.
This issue for me was caused by either a fire extinguisher in my backpack or a stack of wood (for fireplace).