I had the same problem and got some advice from another notary who helped my fix this. There are two different drivers available for Brother printers. One is the CUP driver (don’t use this one) the other is BR-Script 3 (Use this one). You may need to dismount the printer and the CUP driver if that’s what you’re using. Set up a ‘new printer’ using the Script-3 drivers.
Once driver is installed pick a default page size in the MAC utilities, then set the Print utility in Adobe to allow Adobe to select the paper size.
You will also need to set up the printer telling it which tray has which paper size. You do this using the menu on the Printer itself. The paper work that came with your printer will have these details.
So far this has worked for me. Good luck.