I've started using iCloud Drive to sync my settings in SkySafari Pro 5 for iOS. I have an iPhone 7 Plus and an iPad Pro, both running iOS 10.3.3 with all apps updated. I've noticed that changes I make to my settings in SkySafari on my iPad (such as renaming my telescope or adding an eyepiece) do not sync to my iPhone. But changes I make on my iPhone sync normally (and quickly) to my iPad, once I send Sky Safari to the background, as your documentation suggests. To confirm that the settings are syncing, I've been launching SkySafari to check to see if the changes are visible. When they aren't, I force quit SkySafari on my iPhone and relaunch. When the changes still aren't present, I check the actual "Equipment.txt" file using the iCloud Drive app for iOS. The changes are missing from there, too.
However, when I check my iCloud Drive in the Finder on my MacBook Pro 10.12.6, I've noticed that changes made on my iPad DO sync there. They just don't sync to my iPhone. Changes made on my iPhone sync to both locations.
If I manually edit the "Equipment.txt" file on my Mac, by opening the file from iCloud Drive in the Finder (which launches TextEdit), the change I make syncs to my iPad but not my iPhone. For example, if I add the letter "A" to the end of the name of my telescope, that change will sync to my iPad, but not my iPhone.
Lastly, I've noticed the following:
- Make a change on my iPad and send SkySafari to the background.
- Verify that the changes sync to my Mac (view file in iCloud Drive).
- Verify that the changes have NOT synced to my iPhone (view file in iCloud Drive or launch SkySafari)
- From the iCloud Drive app on my iPhone, delete the "Equipment.txt" file.
- Wait a few seconds.
- The "Equipment.txt" file will automatically reappear on my iPhone, with the updated change now present.
I've tried cleanly shutting down my iPhone and powering on. I've also tried deleting the app from my iPhone and reinstalling.