With the new iOS 8 release, we have seen a few users have some issue with logging into naturalForms when their tablets are out of memory.
What occurs is that the user opens the app and the log in screen appears. They enter their email and password, but the server address is grayed out with the following - https://server.domain.com.
We have found that if the tablet is running out of memory, the iOS is wiping out the device's cache file. This is where the server address is stored.
Therefore, please free up some memory on the tablet. The easiest way this can be done is by removing unneeded apps, videos, or photos.
Once this is completed, you will need to uninstall naturalForms and then re-install it from the App Store.