G28 G91 Z0 no longer working

[RecceDG]

I have an Inventables XController with GRBL.

I added a SuperPID spindle speed controller which requires a hardware spindle activation connector. So I downloaded the Inventables fork of GRBL (https://github.com/inventables/grbl-xcp) and flipped the bits in config.h (define INVERT_SPINDLE_ENABLE_PIN define USE_SPINDLE_DIR_AS_ENABLE_PIN) that enable the SCK pin, recompiled, and installed.

This also moved me from GRBL 1.1g to 1.1h.

Everything is working, save that previously, "G28 G91 Z0" would - as expected - raise the Z axis up to the home position. Now that same command is moving on X and Y to the position defined in G28.1

Any idea why?