new outlook not syncing with gmail, no error message

This is how I solved it - not for the faint of heart. The email address I am using is my business address, hosted by a website provider (e.g. ******@mybusiness.com). My 365 email address was the .onmicrosoft.com one that gets automatically generated - since I am not an IT person I pretty much ignored that address and all it ever seemed to have as traffic was MS admin autogenerated emails. However, that was the only address that I could now use to send a teams message - not cool when I am running a business and I want to use my business address. Though, only a couple months ago, my business address worked fine...thanks MS for the updates!

So this is how I fixed it, and this took a good chunk of two weeks in the downtime and nights to teach myself all the steps. I can't include them all here, honestly, some of it was trial and error so my more detailed notes are imperfect and a couple of the orders may be out of step, and each step is hard if this is not your usual thing and don't speak IT. There is plenty of youtube and MS help centre stuff out there - some of it is a bit old, sometimes a bit contradictory, but it was the ticket to piecing together the puzzle:

1. You want to add your business or other email hosted by an external provider as the one to use teams etc
2. add that external domain (e.g. mybusiness.com) to the MS admin centre, add DNS TXT and TTL records to the external <mybusiness.com> domain as provided by the admin center (TTL did not need to match the 3600 seconds MS provides, used the site default)
3. add the business email username ((e.g. ******@mybusiness.com) that I wanted to my 365 account in the admin center as a user
4. create a migration endpoint in domains in the exchange admin center and the associated .csv file - need IMAP server, port and encryption info from the external domain
5. add the MX, TXT, and CNAME records in the hosting platform for the email I want to migrate over (if your email is/was hosted elsewhere)
6. run the migration batch
7. Boom! Actually, more like ripping a bandaid off then boom.

Sometimes it takes 15 minutes or so for the servers to see each other on any and all of these steps, don't manically hit refresh like I did over and over thinking I had screwed things up...

You can always pay someone for software to do this, I am just cheap and a sucker for punishment and I figure I need to know this stuff. Good luck!

I'm also looking for a solution to this! I re-installed my gmail account and it works somewhat but it can take 5-10 mins to download or send emails. Calendar invites from others all looks "tentative". Problem on my Mac from one night to the next morning. Outlook still works on iPhone and iPad. Would be helpful if Microsoft could fix this given the number of posts!

Use "Thunderbird Client". It's free too, and syncs with Google +++

Started working without changes in the last two days (on both PCs). No communication from Microsoft that a software update resolved?

Yes, that fixed it last week for me too. But a pain because I had to sign into gmail on all my pcs all over again, regardless if it was the New Outlook or old Outlook but it works.