Not able to add any custom ringtone
Using ringtones on the Moto G Power: You can use default notification tones or explore other options to personalize your MultiTimer application.. In case the alerts don't work, please email us at email@example.com so we can look into your issue and assist you.
Set ringtone for app notifications
When you are unable to add custom ringtone on Motorola Moto G-family devices
This problem has been tracked since 2018 and is not app related, but system related.
The problem occurs after updates are installed - the phones revert to the default ringtone.
You can try some checkpoints here. Hopefully this will help:
Delete the original 'Ringtones' folder, manually created a new folder of the same name and then pasted a copy of the .mp3 into that directory.
Do the same with the 'Notifications' folder.
Go into safe mode and then reboot your device.
Feel free to send us requests at firstname.lastname@example.org to clarify features that you are not sure about.
We’ll help you figure it out.