IF statement, conditional formatting

Good afternoon,

I have written a basic IF AND statement 

=IF(AND(L5>1,M5>1,N5>1),"2","1")

and even though this is producing what I would like it to, the conditional formatting element has stopped working as have any formulas based on this cell.

I have formatted the cell as number but to no avail. As you can see below, the previous 3 columns produce the %s I need, but the final column does not.

This is my IF statement from the O5 cell. The error message is linked to it being a locked cell. I have locked and unlocked to no avail. Apologies if I haven't given enough information. Please ask for more if needed. First time post.