"Invalid Input" error when trying to set a service center number

On an LG G4 (Android 6.0), I'm unable to send SMS messages, when I called my provider they told me that I need to change the Service center number in the Messaging app settings. Currently it's +7, when I try to change it to the correct number (+97253989999) I get an "Invalid input" error. UPDATE ------ When I restarted the device, the problem corrected itself and the correct number was set as the service center number. Does anyone knows what the cause for this can be (it's not the first time this happens)?