Problems with Exchange 365 mail & calendar sync on Outlook iOS

Question

So, first let me say I’m not 100% sure when this problem started but it seemed to start out of nowhere. I believe it seemed to begin happening after I began running a 3rd party integration, but not immediately after which is confusing.

Problem: My Exchange 365 email and calendar do not want to sync for Outlook for iOS. Everything syncs fine on my Windows 10 Pro + Outlook client but not on iOS. (yes I have tried MSFT support which is very persistent at trying to help you.. but yet unable to find an answer)

Notes: My url is registered through GoDaddy

It is the url for my main website, and also for my email addresses.

Nameservers are managed through my 3rd party (due to integration) - Real Geeks (who I did loop in on the support issue with Microsoft but to no avail), who runs my website and CRM. The integration essentially allows my CRM to capture all emails flowing in and out of my mailbox outside my Outlook and also to send emails through my domain and exchange server.

So for the longest time I just had my email setup on Outlook for iOS under the “Exchange” login and you login with email & password like normal and everything syncs. Then I added in this integration, and from what I remember there were no immediate problems, but then maybe weeks or a month later I started seeing where my ipad and iPhone weren’t updating things. Messages I’d delete or file into a sub folder on my PC would still be in the inbox on the iOS devices. Calendar appointments I’d add on my PC would not show up on my iOS devices.

I was told the solution was to setup my iOS devices as imap accounts rather than exchange accounts. So I did, and it seems to have worked some, but not completely.

One problem I’m still having is if you add the email as an imap you can’t use calendar in outlook. You can go use Calendar app separate, but not inside Outlook, which is annoying.

Also sub folders do not seem to be syncing. If I go to Sent folder, deleted items, or a sub-folder I’ve created for filing like business receipts it does not seem to update it with work I did at my PC.

I guess.. maybe the only path is either to lose the 3rd party integration or consider trying Google or someone as the provider of my business email?

Thoughts?