The latest firmware release from Garmin seems to have broken something.
Thanks to Andrew65 for letting me know about this.
I don't know what the changes are exactly, but using some debug output it seems Garmin may have added a new protocol - D1014.
Looking at this, I think it is a new Run Type, possibly something to do with the new Auto Lap functionality? Sadly it's not documented anywhere yet - so I've had to guess the new D1014_Run_Type structure - this invention is currently under test with Andrew65.
Sorry about the disruption - I'll look at it and see if there's any way to avoid it in the future.... I'll also see if I can make some of those changes I've been promising!