Unable to Sync - Couldn't sync the daily activity data

I get the same error on my Mac with Garmin Express. Syncing with the iOS app works fine, though, so it appears to be a problem with Garmin Express for Mac.

Thanks for the suggestion. Didn't work for me unfortunately. Appreciate it though

I have the same problem. If I close GC on the Mac and reopen it when the fenix is already connected it works correctly. But if I disconnect and reconnect the fenix with open GC I get the error. Nobody knows how to solve?

This has been happening to me for 2 months now. Does Garmin even care about this issue?

Same here. It's really annoying.

Would you mind adding some more information please? Not sure whether the problem is Garmin Express - the program on the computer, or Garmin Connect, the website at https://connect.garmin.com/modern/

Not sure whether this is the watch or GC. Mine also would not sync daily activities this morning to GC on iPhone X. Plugged watch into laptop and tried to sync via GC and it came up with a message saying it couldn't sync daily activities because the device was not set as the default activity tracker. I checked the settings and of course it was set as the default activity tracker. I manually sync'd again and it worked.

I'm inclined to think that this is a result of the beta and not GC but I could be wrong.

Garmin Express syncs with Garmin Connect on the interweb. Is you device set as the default tracker there? Saying that, if you’ve only got one device it should be set as such by default. Have a look at the setting on Garmin Connect online. Check them, change as necessary, then sync via Garmin Express, to your device. Life seems to have got a little complicated with GE, GC and GCM. There was a time when GC (internet) was the master and any changes made there were synched across everything. Now I get a bit lost whether GCM (mobile) takes a lead over GC (internet) at times. That said, I still treat GC as the lead and sync settings that can be changed there down.

FWIW I have a 5s+ on 5.57b and a 935 attached to my Garmin accounts. Synching works fine from mobile (iPhone X) or GE.

I solved this issue after I enabled "Auto Upload Activities" in phone ( I have iphone7, mac, Fnx5x+, latest software ) MobileConnect - Devices / General. The watch don't sync with phone only. It's a cloud service and with setting disabled there is no sync. I blame Garmin for lack of explanations.

I also have same problem. iMac, Garmin Express 6.10.10, Fenix 5 FW 12.
I have attached a screenshot, unfortunately I'm using the Italian version, however the translation is below
During synchronization a I get a popup with the title: "Impossible to Sync" which says: We couldn't sync the daily activity data (i.e., steps taken) from this device because it's not set as your activity tracker.
However my Fenix5 is set as activity tracker.
There are no errors when syncing from my android phone.
I also use an XT920 and it has no problem at all when syncing. Of course the XT920 is NOT set as default activity tracker.
Anyone was able to solve the problem? It seems that synchronization is fine, ie. I can find sport activities recorded with XT920 on Fenix5, not sure if there's anything else missing.
Many thanks in advanceciq.forums.garmin.com/.../1439838.png