I'm not sure the extent at which causes this bug but it's one that can be caused by multiple issues,

Players being registered in the DB or MYSQL with special characters in their names, or if you're using a sv.db, players with special characters in their steam name can break item status from updating on the client, and for any character or player called after that player.

a good example I have is the following: (note I've HAD to add both the equip and de-equip option to be visible as a half work around but the bug still causes problems sometimes with stat bonus desync.

This item is equipped. I will de-equip it using the menu.

After clicking de-equip

The item is successfully removed from my hands, however, nutscript on the client treats it as if I never de-equipped the item

I'm not sure how to fix this, I've tried numerous different tests but it seems like a variety of things can cause the bug. I'm debating on if I need to just do a full reset of everything, or if there is a known probable cause/compatibility that can be installed to fix this.

Some other Information:

With this bug active, you can still toggle on and off radios, however the client still treats it as if you don't have a radio if you try to set the channel/frequency, (this can be dealt with by dropping the radio and opening the UI to edit it's channel, however trying to do so in your inventory nets the response "you don't have an active radio"