Probe/homing weirdness on CoreXY (no replies)

Hey everyone, I've recently built a HEVO, and I've got everything homing properly (I think.) It homes to the front left corner. The bed homes nicely to meet the probe. When I do bilinear probing however, it appears to be moving the z axis in the wrong direction, causing it to scrape more and more with each probe point. After this the print starts, and the bed moves up even farther.

I'm not super savvy with Marlin, so I'm pretty sure I've just got something a bit off. Anyone got any ideas what it might be? I've attached my configuration.h, hopefully that'll shed some light on the issue.