Event webpages don’t allow signing up

Webpages for individual events seem to have a problem with loading dynamic signup data or something, instead of the usual + signs the squares are solid orange and they don’t do anything:

Also no indication if one has already signed up, and the numbers of participants under “toggle event details” all just show “–”. Tried with two different browsers, no change.

Now the + signs are back but don’t actually do anything, still no participant counts in event details either.

Now the + signs are for some reason gone again but at least signup works as do the event details.