Data Validation Error in Drop Down List

[snaplink22]

Hello,

I have a drop down list that includes four cells (B13 to B16) in cell A2. One of the cells that is being used in the list is blank so users can swap back to a blank cell if they want to change their selection. The challenge I'm running in to is that when a user changes their selection back to the blank cell I get a Data Validation error. This does not impact my sheet, except I keep getting questions from the users as to why the cell has the green shaded corner edge when they do that. Do you know of a way to correct this issue?

 

[snaplink22]

Yes, when the green triangle appears, it means the cell content triggered one of the checking rules.

Which is a bit strange seeing how a blank cell is part of the drop down list and the ignore blank cells check mark is not checked. Anyway, thanks again for your help.