[OPi Win boots legacy but not mainline?]

So I have a weird problem that I haven't seen yet, so forgive me if its already been answered. But for some reason mainline kernels (bionic and stretch) both bootloop at the same place. Seen below:

 

The board boots perfectly fine on legacy kernel though. I'm using decent quality Samsung SD cards, and I've tried every combination of usb cable/powerbrick as well as the barrel jack so I'm not sure what the snag is.

[Guide: How to use Touchscreen + LCD on H3 devices]

I was able to get everything working on mainline kernel w/ mate installed, but somehow the touchscreen's left-to-right is acting weird.  The cursor moves opposite to how I'm moving the pen, but only in the x-direction. It follows the pen up and down still. If I change the rotate option in to 270 instead of 90, the y-direction gets mirrored instead of the x. Is there an option to only mirror one axis?