Switchres not switching to correct Hz - retroarch px68k core

[BazookaBen]

I'm trying to play the Sharp x68000 version of the Thunderforce 2 since the Genesis version's limited FOV is making me mad.

I've created a 256x256 @ 55hz mode in the EDID, but Retroarch just runs at 55.00 hz precisely, or at the exact timings I have in the EDID. In my understanding, the Sharps 55hz mode was actually 55.45hz.

So if I try to play with vsync off, my FPS is reported as ~55.75hz, with vsync on, it will be ~55.09hz. Both are missing the mark and give some degree of stuttering. Vsync on is playable but has a stutter every 2 seconds or so.

So is this a problem with the px68k core itself, or maybe my settings are wrong? Switchres is set to 15kHz and native resolution.