I've run into this issue many times but have been able to fix it by finding the item and untagging it. But I've come across an item that appears to have fallen through the world and I have no way of untagging it and it is just constantly there. Does anyone know a solution to this? I've tried saving/loading and it hasn't done anything.

Picture doesn't show anything.

You can't untag things without line of sight.
... no idea why not.... if it's electronically tracked, you'd think you could target it that way too, but it doesn't work. :-(