We found the problem but not clear why.
As posted above our code was using a range value of
Ss = "A" & Row & "." & ColNames(UsedColsSht) & Row + 1
s = ws.Range(Ss).value
Note: that a period was used so the range was something like A1.C3 This continues to work in 7 of our 8 systems that we have seen but when we used this format in the excel screen we got a #Field! error. This is a new Excel behavior.
Changing our apps to use a colon instead of a period solved the problem. So the range is now
Ss = "A" & Row & "." & ColNames(UsedColsSht) & Row + 1
or A1:C3
Again it worked in most systems and that cannot be explained. There was nothing in the event logs and the original posting in the header was a false alarm.