Your comments

Can you please give me example files that I can use to reproduce it on my device?
Can you tell me which method you use to switch between tabs? Do you use a shortcut or do you click on the tab?

I tried the following:

  • Hit Cmd-N to create a new file
  • Type text into the file
  • Hit Cmd-N to create another new file in a second tab
  • Type text
  • Hit Cmd-Z -> this deletes the contents in the second tab, but doesn't delete text in the first tab
It's great to hear that you could figure out the problem.
Please try to enable the "Debug Log" setting in the connection's settings screen. Tap on the (i) button on the right side of a connection to change its settings. This creates a log file when you try to connect to the server which might help you find out what's wrong.
Thanks for the detailed explanation and gifs - that's a good point. I've added it to my todo list.
Unfortunately this is a bug in iOS 8. I have reported it to Apple and hope they'll fix it in an update.
Hmm. Which part doesn't work? Do you see iCloud as an option in the folder selection screen?

I just tried it on my device and it worked.