[Obm] Thunderbird + plugins

[Benito Chamberlain]

Struggling with Thundebird and obm calendar syncing.
Here's what I have
Thunberbird 38.2.0
Lightning 4.0.2
Obm-connector 4.1.0

I have the mail and obm-sync server setup, I can connect and synchronize 
my calendar and address books.
However , whenever I invite any attendee and I choose notify, I click on 
sync and immediately I get :
" Error during synchronization "

If I add an event and don't invite any attendees , it syncs to my 
calendar successfully.
Also I have looked at the users Right management under Calendar 
(webinterface) , and added the other user to read , write access.
No difference. When I invite via the web interface , it gets synced to 
my Thunderbird/obm calendar successfully. Just doesn't work
when I invite from withing Thunderbird.

Can you please give advice on where to start looking for the problem? Or 
could it be a bug in the tbird / lighting /obm plugin ?

Kind Regards
Benito
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