My father's first wife was mis-named, so I corrected that to 'Mary Lena Petty'. I also corrected her birth date, but I was unable to find a way to correct the fact that she was NOT my father's sister, so my relationship is wrong. I did leave some comments, and I was unable to delete a comment that I messed up (seems like I should be able to do that). 'Lena' died before I was born, but I know that the changes I made are good because I grew up with her 2 daughters, one of whom is still alive.
To find your comment, in the Family Tree web interface (not the mobile app) go to My Contributions: My Changes. You may have put it somewhere you did not intend.
I found a Mary Lena Petty you worked on recently, but I don't see her attached to your father's parents, or any sign of a recent correction. If you'd like to share the person ID (PID) where you see the problem, someone here could take a look.