*version 14.17 but has been always not 100% right
- seemed to start after I just changed screens to check stats, then carried on after that
- loss of resistance control, only recovered ( setting the correct target for the rep) after hitting lap button, it got stuck on previous target even though the next easier rep had started
- I tried "resuming later" the workout so I could check sensors were connected & no issues there
- this issue rarely happens with the Zwift Hub when connected to 3rd party app ( then just logging a free ride to record the Watts )
- can BLE be supported on the watch if it's better?
- Garmin Forerunner 255 ANT+ seems to be certified for the ANT+ FE-C DEVICE PROFILE but I wonder if something's getting clogged in its memory causing it to have "too many things to do at the same time" ?
- I think I might record the data using separate hardware at the same time & compare the FIT files side-by-side
for comparison, a similar workout without any issues - the main bit is in ERG mode so when it's working there is virtually no variation in Watts :
yesterday's Garmin-suggested recovery workout @ 123W : no issues at all
( update Tue 28th Feb )
I've been working with Support and going to try turning off Wifi router which is also in the kitchen. Channel (1) not in ANT+ radio range but main router ( at other side of house ) is on channel 9-13 ( peak at 11 ) which would interfere if strong enough. Maybe going off grid completely would do me the world of good!!
Findings coming soon 
( update Wed 1st March )
With 2.4GHz wifi transmitters ( 2 of them ) disabled - no drop outs at all today :
so maybe BLE is better than ANT+ at handling any errors?
( update 2nd March )
Still getting drop-outs & 2.4Ghz wifi still off:
the issue didn't correct itself so when I hit the lap button the watts for the next rep were fine - see image
Fri 3rd March : no issues
Workout notes: 15 x ( 4 x 30s blocks of custom power targets to stress-test ERG mode ) - 60 reps in total, 30mins
Phone status : Airplane mode enabled | BLE off | Wifi off
Router status : 2.4GHz off | 5GHz on
Zwift Hub : Spin-down calibration done
Zwift Support recommended a spin down per use yesterday
Sunday 5th March Update
All the same conditions as above, except:
Workout notes : Power Curve Targets
New insight : respiration rate drops out at the exact same time!
respiration is never an issue where there aren't 0W issues:
There seems to be some coincidence where the drop-outs are in relation to the main intervals:
Note there is an existing bug where the target shows up as 0W, so maybe the software on the watch is setting it wrongly to 0W??
Mon 6th March
Power drop-out whilst going for a run.
No external sensors attached and I didn't stop running as can be seen from the pace :
