Excel plugin - Error occured while getting files from zoho

Excel plugin - Error occured while getting files from zoho

Hi,

I am using Zoho UI and also the MS office plugin mainly to "sync" my local spreadsheets with the one on Zoho.
While the online UI works fine, since today I got the error message from Excel zoho plugin when either trying to open from Zoho or Save As ->  Error occured while getting files from zoho
Then I must click OK and it opens the zoho docs windows (files from docs.zoho.com) but of course it's blank so useless.

Any idea ?
Thanks,
Chris