I have the same issues, also with activity maps. After trying everything possible, all garmin connect functions work if I reboot. I the have a period of time with everything accessible before it will quit working again. It is the only wavy I have been able to work around the issue.
all garmin connect functions work if I reboot
What browser do you use? Did you try clearing the browser cache (temprorary internet files), instead of rebooting? Or deleting the cookies for *.garmin.com? Or using an alternative browser? Disabling extensions such as ad-blockers for that domain (don't worry - there are no ads on Garmin Connect Web)?