Circular Ref - Formula Popup

[CraigS26]

My intent here is to spend 60 seconds Max of your time to see IF a Troubleshoot method is suggested aside from the Re-Formatting I've done.
Likely after an Office Update this data sheet of Macrium backups now generates the Circular Reference popup that Re-formatting all cells has not fixed.
There are 3 different Drive groups data like R ...
All cells NOT in a data Column are formatted as - TEXT.
Date is Date format as seen
TYPE and SIZE are TEXT format
TIME and LENGTH are CUSTOM ( h:mm:ss)

I can live with this BUT is there Any idea HOW to stop the popup ..... that for years didn't occur?
-- Forum 640 max pixel Width limits popup & data view. --
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[HansV]

On the Formulas tab of the ribbon, in the Formula Auditing group, click the arrow on the right hand side of the Error Checking button.
Can you click on Circular References? If so, it should show which cell/cells cause the error.
Click on the cell/one of the cells to activate it, then inspect the formula in that cell.

[CraigS26]

Thank you, Hans!
That suggestion showed cell A20 as the culprit, which as you can see is a color blank cell.
I clk'd Trace Error and it mentioned something like wanting a Value there (actually an "error value" when I took a 2nd look) ) .
I simply typed the number "1", saved, and No Popup.
As usual, it makes no sense to me but I'm happy!

EDIT: It gets better: I hadn't read the last sentence correctly to view a formula - Went back and Deleted the "1" I typed, saved, Open ... and No Popup. I'll know what to try SHOULD it return.

[HansV]

Weird, Excel must have become confused for a while...