However it does sound like something that will happen if the owner fills up the phone memory. Uninstall a few apps and see if it can save again.
As to the W10 issue, contact the app's author why their app failed.
I have a Samsung S6 smartphone. The phone feature will not save new contacts. I can initially save them, but after a while any new contacts will become unsaved. A phone tech told me to back up my phone on my computer with Smart Switch, reset my phone, and then transfer all my data back to the phone. I downloaded Smart Switch to my computer, but when I go to open it, I get an error message that says, "The application has failed to start because its side-by-side configuration is incorrect. Please see the application event log or use the command-line sxstrace.exe tool for more detail." I am using Windows 10.
Burt

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