I spoke with Yamaha about this anomaly, and they are as baffled as I am. I opened a case, and they are looking into it. I also ordered the pedal unit that is "supposed" to give the feature I need, but I'll have to modify the structure, because I'm not using the home furniture stand. I need to make this road-worthy if I am going to keep using it. I like everything about it except this damper/sustain issue.
Make the layered strings sustain, and make the split bass IGNORE sustain.
Now, we wait.
"Even the darkest night will end, and the sun will rise" ... Victor Hugo