Hub not syncing 1 email

Every email was working fine this morning. Turned on my laptop and saw some emails that hadn't come through. Checking that Addy on keyone, it kept saying 'syncing' and then it said hub not responding.

I've powered down, reset my password n but the hub will not bring in that one address (the other 3 seem okay)

Any ideas?

I gave up and disabled the hub, did a soft reset and re-enabled the hub. I had to add back all my accounts manually. just wish I knew what happened, though.