OK, I'm really stuck on this one...
I've written a simple index match formula...
=INDEX({TSRCC}, MATCH([Unique Event+Session Date]@row, {TSR Event Name}, 0))
It worked perfectly fine. Then when I saved the sheet all rows changed to a #NOMATCH error.
When I rewrite the formula, it worked again, then when I went to save, it failed again #NOMATCH.
I'm so confused, any ideas?