Sounds like a storage / file system corruption that wiped all of the app's storage.
I routinely "upgrade/reinstall" the app during development dozens of times a day, on multiple devices, and never seen this over all of several years.
And yet it seems to happen "out in the field" from time to time. Very rare, very unpleasant, but I think not related to the app itself.
Yes, unfortunately, you'll need to recreate your accounts / settings. I also recommend wiping the app's data first, to be "more" safe. This is in system settings -> apps management.
And BTW - Aqua has a built-in backup / restore facility, and since 1.4.something, you can store the backup file in Dropbox (or restore from there).