Some activities on my.zwift.com lead to a throbbing multicolored Zwift logo

I scrolled back to my first activity on my.zwift.com (12/15/2015), but when I selected it, I was taken to a page with a throbbing multicolored Zwift logo. Ten minutes have gone by, and still no activity details. Just a big Z.

The same thing happens for my ride on 7/13/2018, and many others. In fact, this seems to be the case for all activities prior to 8/2/2018.

See https://drive.google.com/file/d/1v7GrKzYOzhf4XFs0Xehc-NtGIX7Vm6Yr/view?usp=drivesdk