Hey all, some good news. After identifying what was common across most of the reports of this issue (using this thread!) we finally today got it to reproduce 100% of the time. Once we had that, we tracked the issue down in about 15 minutes.
It appears that if you let a device go out of range (ie, walk away with your heart rate strap), or let your cadence device go to sleep (ie, don’t pedal for a while), our re-scanning code that starts searching for the missing devices can sometimes conflict with sending commands to the trainer from that point onwards. This would be why it was impossible for us to consistently reproduce, and also why 100,000+ other users were Zwifting happily over bluetooth and reporting no issues.
We’re putting together an update now, and will try to get it submitted to apple in the next 48 hours. From there it can take up to a week to get approved by Apple - so in the meantime, the workaround would be to pair up your devices only once you’re ready to ride. Sorry for the inconvenience, but it was really due to the posts here that we were finally able to track such a very specific bug down.
It could be possible the bug could also happen ‘organically’ mid-ride if a device drops out for a long enough time, and that case too is probably handled with this fix although we’ve not fully verified that case yet.
(NOTE, another case that could cause sim/erg not to work is by performing a spindown, but cancelling it without making it through to success. This too will be fixed in the update).