Omni Sync server stopped working on iPad

I use OO on Mac and on iPad. Suddenly it has stopped working on the iPad.
Today, I went to the gear icon on the iPad version and went to cloud options and there was no username and password present in the list of accounts so I entered my user name and password again and it seems to be re-downloading the entirety of my documents afresh.
I quickly made a back up on my Mac first, as this could have caused an issue and I need all these outlines for work. I am a bit surprised by this behaviour.
Is there a time out on the iPad and will I have to do this again periodically? If so, I could set a reminder to re enter my details the day before so that it doesn’t catch me unawares at a difficult time. is this a bug? Is it known about?

Seems to be good again but I have had a couple of weird instances of being told that I don’t have permission on the Mac to edit the file and need to make a duplicate for discard the changes. Hope this is isolated.