Mininova midi playback drop-outs

Having problems with drop-outs when playing midi parts out on a Mininova (connected by USB).

When rewinding and going over the passage a second time there are no drop-outs, but after a bit they resume…

(Elements 8.0.40 (64 bit) on Windows 7)

Advice given in https://www.steinberg.net/forums/viewtopic.php?t=79472 about setting Timecode Source/Target under “Transport” didn’t help.

Firmware on Mininova is 1.4b7

Any ideas? Thanks