Hi,
Because of changes made by Google and required of app developers - we cannot use *files* (filenames) anymore. If we try to, Android will crash the app (intentionally. "you're doing something forbidden").
That's really a question for Google and device manufacturers. Google is forcing all app developers to "optimize" (ahem) their apps for Android 8.0.
If your phone runs Android 8 or newer - you may have better luck with 1.18 version - where notification "appearance" (sound / vibration / etc) settings are now in Phone Settings (again a Google requirement).
You can find detailed explanation here
https://www.aqua-mail.com/forum/index.php?topic=6915.0+ Android 8.0+: notification settings (sound, vibration) are now in phone Settings (a Google requirement).
Actually it's more than that - this version has "target = 8.0" as required by Google.
The appearance of notifications (sound, vibration, etc.) can now be changed *only* by user.
An app can pre-fill some defaults, but that's it, it can't change how a notification appears, only the user can.
Explanation from Google:
https://www.youtube.com/watch?v=zGIw4MIJn5oNow some manufacturers have optimized their notification schemes and made their notification Settings better. As for Huawei, Samsung - it seems that they haven't done that yet.
Thanks,
Nadia