IOS app stuck on "housekeeping"

The app only shows a screen with:

Updating...

Dropbox needs to do some housekeeping. This should take less than a minute.

I opened the app an hour ago. What is it doing? Why is it taking far longer than a minute? Just curious if anyone else is seeing the same behavior.

I tried searching the Dropbox Help Center but (unsurprisingly) found it not very helpful here.