Hi,
I have been experiencing this same issue with certain built-in sounds:
1. Select the built-in 70sSuitcaseBallad voice
2. Hold the sustain pedal down and play a bunch of notes, enough to hit the polyphony limit (256)
3. Hold down a final chord of keys and lift the sustain pedal.
Instead of the expected behavior that the final chord of keys sustains their sound b/c they are depressed, the Genos instead will go totally quiet. That's bonkers! It's clearly a flaw somewhere in the Genos.
This has been driving me nuts since I got my Genos over a couple of years ago. I guess I just learned to live with it b/c it doesn't happen with every voice, plus you have to seemingly hit the polyphony limit. But lately I've been playing more electric piano voices and this behavior makes some of them unplayable.
Finally took some time to try to figure out what the problem was. Repeating the same experiment above with the Chorus effect turned off fixes the problem. I guess this is equivalent to playing the 70sSuitcaseClean voice which also doesn't have the problem. So maybe that means that the issue is caused by certain effects. I experimented with varying effects and found that chorus and some other effects cause the problem, while other effects don't. But the effects by themselves aren't the issue b/c other voices work ok with them.
Last night I discovered that Yamaha is now offering Genos expansion packs for free at their online store. So I downloaded this pack that contains electric piano voices:
https://shop.usa.yamaha.com/en/downloadables/sound-expansion-library/premium-packs-voices/vintage-keyboard.htmlWhen I tested the voices, none of them had this sustain issue.
I've found several built-in voices in Genos experience this issue...various electric piano, guitar, and string voices.
The workaround seems to be to find expansion voices and load them as replacements to the built-in voices. I'm now scouring eBay and other online stores to find replacements for the voices I most commonly use that have this issue.
Hope this info is helpful. The Genos is a wonderful instrument, but this issue has been driving me nuts and causing me lots of anger when I play...nothing worse than the instrument cutting out and ruining an otherwise beautiful performance.