I have an unusual case with Excel and #REF!
error. I've this formula:
=INDEX($N$621:$WO$621;SMALL($N626:$WO626;2);0)
which gives me sometimes a proper value and sometimes gives me a #REF!
error as a result. Link here.
I checked all my cells and everything is in its place.
I'm posting this Excel sheet. The reference error occurs in column L, at 626 row and below.