No more Mails from connected accounts like gmail since a few days.

I am using the connected accounts in office 365 for the last 2 years. Had no major issues with it until recently, besides the fact that email is refreshed every hour and there is no way you can change that. However, since last Friday one of our accounts stopped syncing. Reason unknown. Even office 365 support is not very familiar with the feature, cannot provide a reason for this and their only suggestion is to delete and recreate the connected account. Did that and still only 1 in 5 emails was syncing, the other 4 in 5 were not.  Since the new connected account didn't show the option Leave messages on server - it's selected by default and you need to make a trick to show it, I deleted again the connected account and unchecked the Leave messages on server option, thinking this might fix the issue. So the faulty code in connected accounts, went to transfer again 1 in 5 messages in Office 365 but deleted all, including those not transfered!!! So lost tens of emails with no easy way to recover, any search in Office 365 data revealed nothing.

The best part is that their support manager, claims that this option does not delete POP3 emails etc., based solely on his own wrong interpretation of a MS document, without even testing the feature.

Of course it only gets better. Today my account is also not syncing properly, the pattern seems to be any email with an attachment bigger than 400KB or so, is not syncing. 

So, there is definitely a serious issue affecting connected accounts. Since support is not helpful at all, and we had also recent issues of not been able to send any emails for 5 days, we are planning to stop using Office 365 Email ASAP.  Extremely sad for somebody using MS products for 27 years and a MS Partner company but true.