I've stumbled across this problem today. When using the sustain pedal, notes would not retrigger once I exceeded the polyphony. So I looked at the manual, and here's the issue: in the relevant manual page (p. 53, "Key Modes and Unison Mode"), it
states at the bottom "Key Assign settings are only relevant to Unison mode. They do not affect polyphonic playback".
That's very misleading, because they do affect polyphonic voice-stealing. The solution for fixing the retrigger issue above is of course as explained here, to set the voice mode to one of the retrigger modes. I had to come here to check this, as I could not figure out what to do to fix it (and thought it was a major bug).