Profile does not work

The information on my profile has disappeared. (Already before the numbers of followers and followees were missing, but now even the Gravatar image is gone). This can be due to a misconfiguration, but I did not find it out. Is it possible, that the reason is that my username is written with a capital letter in the beginning whereas my fediverse handle is @heinz@wittenbrink.net ?

The page I need help with: [log in to see the link]