@ocnbrze ...thank you for letting me know about not displaying the EMEI #. I should have known that.
To answer your question, I manually updated the system software. After phone installed the update and restarted, I would check again to see if there were more updates until on the fourth time, the system told me that there were no further updates. I then proceeded to install my apps and configure the phone to my liking.
It seems the Android Forum Team has deleted that screenshot of my system info, as I cannot see it anymore. Thank you team!
And thank you for the welcome, MoodyBlues.
I don't give up easily. That said, I found the fix!!
1. Go to 'Settings'.
2. Then 'Apps'.
3. In 'Apps', once again, tap 'Apps'.
4. Tap on 3 dots on top right corner of screen. From pull-down menu that appears, select 'Special access'.
5. Tap 'Battery optimization'.
6. Look for 'Essential Apps', tap it and choose 'Don't allow'. (Side note...'Essential Apps' may not appear on your phone. I checked my Huawei P20 Pro and it was not there. I also had no push notification issues with Yahoo Mail app on the P20 Pro)
That's it. I sent myself an email from my gmail account and voiIa...I received the push notification from my Yahoo Mail app. Who knew? Amazing.
Just to let you know, I quadruple-checked it. Meaning, I changed the setting in 'Essential Apps' back and forth from 'Allow' to 'Don't Allow'. Every time I was in 'Allow' mode, I sent an email from my gmail account to my Yahoo account and would not receive a push notification from Yahoo Mail app. Changing back to 'Don't Allow', I followed same procedure and would receive a push notification from Yahoo Mail app every time. Did not need to clear cache, restart phone, uninstall Yahoo Mail app, etc. while double-checking the settings in 'Essential Apps'. So, it's pretty safe to say, that THAT was the problem. I really hope this helps people who are having the same or similar types of issues with push notifications.
@MoodyBlues...I hope that this fixes your problem with your Venmo app. That said, it's a curious thing, from the apps installed on my phone that
can receive notifications, that before I discovered the solution, they all received push notifications. Except, of course, the Yahoo Mail app. It would be interesting to know why this solution (so far), only affects the Yahoo Mail app.