I’m seeing what sounds like a related issue: I’ve got a mid-song tempo change to h=60, and then accel poco a poco up to q=180. However, when playback hits the accel poco a poco, it seems to jump to q=60, and then accelerate from there. Playback is as expected if I change the initial tempo to q=120 instead of h=60.
Perhaps all relative tempo changes are computing off of q’s, regardless of the unit used?