I am seeing mycroft.client.enclosure:read:75 - ERROR - Reading error: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte in mycroft-enclosure-client.log.
This fits nicely with line 75 of mycroft-core/mycroft/client/enclosure/init.py, def read() - which was last changed on July 5 for a improvement of the stop button. Since ca. mid July I am having the issues with the Mark-I faceplate.
tail -f </dev/ttyAMA0 outputs all kind of messages like mycroft.stop, volume.down, unit-enable-shh - so the faceplate/Arduino itself works but the enclosure client in mycroft-core is broken and not handling the Arduino messages properly