You are using xapo web based one or the phone based one? I don't know much about the web one, but maybe you can try to clear your cache or check if its down (i think mostly it'll say its down for you, so maybe you cam just skip to clearing cache) or you can download the phone app, it works fine
I'm using web (tried on 2 different PCs - win7 and win10).
Wrote to xapo support but still no answer from them.
Weird.
i tried it just now, but it's work fine at my place.
maybe you can check your internet? or even clearing your browser cache? and how about using other browser too?
NB: my PC is using Win7 though