Garmin Connect FTP --> 'An Error Has Occurred'

Hi everyone,

When I want to check my Functional Threshold Power in Garmin Connect, there is a pop-up saying 'An Error Has Occurred'.

Is this a known problem?

A bit of context for my situation: I do a training on Zwift, which is (currently) synced to Garmin Connect.

I also record the training on my watch as an indoor Cycling activity because the Zwift-activity doesn't generate a VO2max value and some other metrics.

I deleted the Zwift activities, and kept the Indoor Cycling ones. This is the only thing I can think of that is a factor on my side.

Any ideas?