Is there an issue with Marlin Firmware RC8Bugfix Core XY Drifting to the left?

Hi all,

I just built a Core XY printer (microcube). One of many other printers I have, this is my first CoreXY. I started with Marlin RC8BugFix. The printer prints the 3dbency just fine, but trying to print another, larger object (not taller), the head starts to drift to the left. Perhaps I need to turn the current up a bit more...

Anyone else out there with a CoreXY on RC8Bugfix? Any issues with drifting?

Thank you!