Stuck on Synchronizing folder list

I have two exchange accounts, for different domains that use Office 365. 
I managed to add both accounts sucessfully to eM Client, however the status bar is stuck on Synchronizing folder list.

Hi, did your items synchronize at all after the initial setup? What version of eM Client are you currently using?
Are you using any firewall/proxy software on your computer? Do you see any errors from the application?

Thank you,

Yes, the first mailbox synchronized and then i added the second one, which syncronized the folder structure and inbox. then it stopped syncronizing.
I use no firewall/proxy & ther eare no errors from the app.

also It seems disabling either mailbox (so only 1 mailbox is active) rectifies this issue.

Hi again, how did you setup the account? Did you use the automatic setup?
Are these accounts using Exchange Web Services for synchronization?
What version of eM client are you currently using?

Thank you,