I am dizzy from going around in circles with this for so long...
I am attempting to apply a filter to Get Items:

and I get the error:
One or more field types are not installed properly. Go to the list settings page to delete these fields.
I presume the list it is referring to is the list I am trying to get items out of and I presume the field it is referring to is the field I am trying to get items from. But seriously, do I want to delete that column? It's got my valuable data in it.
As a test, I ran the Get Items with no filter, it runs fine and returns 100 items out of the list. Then I added a variable to grab the values from the field I was referring to in my failed filter attempt. It grabs the values fine:

Result:

So, to me, that seems to indicate my Employee/Value field is OK. Would that be a valid assumption?
Can anyone steer me in the direction as to why my filtering attempt may be failing?