Looks like a test firmware is available with a fix: https://forum.silicondust.com/forum/viewtopic.php?f=113&t=68115&p=317454#p317446
Yes they sent me that firmware a couple of days ago. It does fix the problem at the expense of completely disabling power save mode on the demodulator. They are still looking at the power saving issue. At least it works now - hurrah.
Not sure why only 2 people have reported this - perhaps it is a small faulty batch rather than a firmware bug that affects all units. If it was I would expect every owner to have filed a complaint as the unit is unusable with this issue.