My issue has consistently been that none of the built-in Wyze app sounds work as the notification sound, going back through multiple production app versions, so as an Android user I’ve just configured a custom sound on my phone instead. 
You didn’t mention what app version you’re using, but based on the timing I wonder if it’s related to the most recent hotfix. If I wanted to try getting my in-app notification sound to “stick”, then I’d probably try refreshing the local account settings/profile.
This is how I would get a clean copy of my account profile/settings on Android (click to expand):
- Clear the in-app cache: From the Wyze app’s home screen, navigate to
Account ➜ App Settings ➜ Cache File Size ➜ Clear. - Navigate back one screen to Account and tap Log Out at the bottom.
- Swipe the Wyze app out of the running Android apps.
- Long-press on the Wyze app’s launcher icon (on the phone’s home screen or wherever you tap to initially open the app) and then tap App info in the pop-up menu.
- Tap Force stop on the App info screen (may need to tap OK to confirm) and then tap Storage & cache.
- Tap Clear cache and Clear storage on the Storage screen.
- Back up one screen (back to App info) and then tap Open and proceed to log back into your Wyze account/app. (Optionally reboot the phone at this step for good measure and then launch the Wyze app after the fresh boot instead of relaunching it immediately from this screen.)
I’ll be interested to learn of other users’ experience, because the built-in sounds have been broken for me for so long.