Aeotec Multisensor (ZW100) threshold reports break motion sensing?

I have 10x ZW100 multisensors in my setup, half on battery, half externally powered. All have been working fine for 6+ months. I recently changed by bathroom one (running on external power) to add humidity threshold reports in order to switch on an extraction fan.

Everything works well for around 24 hours, but then the multisensor stops sending a report on motion. All other functions continue as normal, including the scheduled reporting (temp, humidty, luminance, UV) and the humidity threshold reports. It’s just the motion reports that don’t work. The local LED continues to fire on motion, but nothing is reflected in the OpenHab log. I have to manually re-initialise the sensor to get motion working again. It predictably fails again around 24 hours later.

I’ve emailed Aeotec about it, awaiting a reply. Has anyone else experienced anything similar?

Setup is:
Raspberry Pi
OpenHab 2.3 (running snapshot Z-wave binding to allow security for entry control devices)
Aeotec Z-Stick
Devices - Aeotec multisensors, dual nano switches, smart switches, garage door openers, Lockwood (Yale) door lock