emails going to the wrong folder

I had a few people contact me to say they had sent me emails, after checking my inbox i couldnt find them.

I then did a search and found them in a sub folder (not junk, one i had setup).

I checked the rules I had setup and there is no reason for any rule to have sent that email to that sub folder.

Is there a way to check what rule is applied to the email?

I'm using outlook online.