I have similar (but not as bad) experiences with my Edge 1000. Randomly it stops uploading via BT regularly and I have to call Garmin and spend 40 min on the phone with them getting it to work again.
Wired syncs by plugging the unit into a desktop are less glitchy but I still routinely have Garmin Express/Connect fail to recognize my device and I have to jump through hoops to get it to work.
Interestingly, I also upload data to WKO+ and I never have any issues with that, it just works 100% of the time.
I also have a PC7, made by SRM. I've never used it because I did not realize when I bought it that it has no back light and I do most of my interval workouts in the dark. Also no GPS, so no mapping, and I use the mapping when I travel or do long rides on unfamiliar routes.
However, the PC8 does have a backlight and GPS. It seems to mostly be used by racing people who have unique priorities but it seems to be well liked by its users. You might check it out.