Outlook on android - receiving notifications, but emails don't show in inbox.

We use Workspace One UEM (Airwatch)  - Msft responded and asked me to turn off Battery Optimization for Outlook and Intune.  ( i had previously only turned it off for Outlook)  But so far this is working for me.    -  Im not sure if you can enable the setting to turn off battery optimization for those apps, but they need to be able to stay alive in the background to pull mail so when you tap notifications, the mail is there.  

https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/outlook-for-ios-and-android/outlook-for-ios-and-android-faq#q-what-does-background-synchronization-enable-i-notice-that-when-i-launch-the-app-with-it-enabled-i-still-have-to-wait-for-messages-to-download-even-after-ive-received-new-mail-notifications-for-them-and-sometimes-i-get-reminders-for-appointments-that-had-been-canceled

I have been sending diagnostic logs to MSFT.  They said for my particular issue, Battery Optimization has to be OFF for both Company Portal and Outlook.   (Tap notifications for new email, no email is displayed anywhere in Inbox)  I have several android devices, Pixels, Samsung Note/Galaxy devices.  It was only happening on my Pixel device.  But I have other users experiencing this on Samsung.  I cannot turn ON battery optimization to reproduce the issue on my other devices.  See this article, its part of their FAQs:  https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/outlook-for-ios-and-android/outlook-for-ios-and-android-faq#q-what-does-background-synchronization-enable-i-notice-that-when-i-launch-the-app-with-it-enabled-i-still-have-to-wait-for-messages-to-download-even-after-ive-received-new-mail-notifications-for-them-and-sometimes-i-get-reminders-for-appointments-that-had-been-canceled

For your particular issue, I would recommend opening a case if possible, if you have followed the steps in this article and try uploading Diagnostic logs to the MS case so they can examine your logs.

I am seeing this same behavior now a month later.  Do you use MDM  (What solution?) or are you using Outlook w/ Android Enterprise work profile?

Hello, I use MDM - Enpoint Manager from MS. Android Enterprise Personally -owned work profile. Why you ask? Maybe you have some helpful information? :)

1.By default Intune Company Portal, Outlook and Authenticator are excluded from battery optimalisation and changing it is locked so I can't turn it on even if I will want. So this tip isn't for us.

2.We will try tip with refresh Authenticator before start Outlook. 

3. Next we will try tip with "Focused Inbox" and "Organize email by thread".

BTW. My users saw of course issues with get notifacations but no visible messages in Outlook and 5-10 minutes refreshing time in Outlook.

3. Switching to another network while trying to refresh the folder, worked for me. (Although both my networks were up and running throughout the session, maybe outlook app has some refreshing to do with this switch, but it's just a guess)

I am seeing this same behavior now a month later.  Do you use MDM  (What solution?) or are you using Outlook w/ Android Enterprise work profile?

Are you using Outlook for work email?  I've been seeing this issue as well.  Exactly as you describe, however its only when I am on wifi network.  I can turn off wifi, restart Outlook app and the mail starts flowing.  (I have 2 other Android devices, they are not having this issue, on the same home wifi network)