Default [Q] [several devices] Corporate email keeps redownloading inbox

Hi guys, any sysadmins on the group?

I'm having an issue with different devices, where they will randomly wipe all the mailbox emails and re-download it, just like when you first activate the email account. It can happen several times per day and can be rather frustrating.
I've seen it happening in:
Galaxy Note 2
Galaxy S3
Xiaomi Hongmi (running MIUI)

So far we're not having that many android devices, but the mobile contracts are being renewed soon, and I fear many will choose to have new androids, which could be trouble soon.
The email account is corporate (activesync), using the exchange's OWA address as server.

It authenticates properly, sets the email software as device administrator, and successfully download all contacts/calendar/emails. Just from time to time, during daily usage, the whole mailbox will start re-downloading for no reason.

Anyone ever saw this issue?

Thanks!