Trouble adjusting date when renaming file

Greetings,

I'm using content match to find the date a bill is due. Then I rename the bill and use the date due in the new name, adjusting the month to when the bill was sent. I do this by adjusting the month back 1 month.

For example: Utilities bill is due 05/27/16. Hazel then renames the bill from something like xyzgenericpdf2016052712.pdf to Utilities 2016-04.pdf. So the month is adjusted from the month of May to the month of of April to show the month I'm being billed for and not the month the bill is due. This is really wonderful.

But today I got a bill that had the date due as 01/18/16. Hazel runs its magic formula and comes up with the name: xyzbill 2015-10. Instead of giving me the date 2015-12 as expected, it gives me 2015-10. But it correctly renames other dates as far as I can tell.

Is this a glitch? The software is up to date. v 3.3.7

Can you suggest a solution?

Thanks for your time and help!

Testing it out here, it seems to work fine. Can you email support with an export of your rule?