Partial Date Matching and File Renaming

Hazel's behavior seems to have changed over the past couple of months. I was successful pulling a month and a year out of a long file name and then renaming the file using that said month and year but I was also adding the DAY and it was defaulting to the end of the month that was matched so that was great. Now the DAY is defaulting to the current date. I guess I could AppleScript something to find out what the end of the month should be and insert that instead but that is a lot of work for something that used to be happening without any effort. What should an unmatched DAY be defaulting to for a matched month and year? I cannot imagine an easy way to come up with an end of month day without using some scripting if the way it is working now is the way it should be working. Looking for some guidance here.