I've faced with the issue that I can't install the app (Big Picture). Although I'm the admin, I couldn't install the app by one click, but received the message that request was sent to the admin. When I went to app requests, I received a message:
'This is a list of apps requested by users including the number of requests per app.
We ran into a little trouble. It might just be a hiccup. Try again in a bit.' It's been few days now and the problem is still present. Earlier I used this app on other projects and everything was okay.