Same kind of problems with fruux. Thunderbird/Lightning on Windows works fine with fruux, Jolla makes a mess of it. Some events show the same time, others will be one hour off.

Test: create and event "Test 12:00" at 12:00 on Jolla. After sync, the event shows on Jolla, fruux and Lightning at 12:00. Hurray! But wait, a few hours later the event will show at 13:00 on Jolla!? There is something very wrong here.

P.S. fruux has an option to send me a daily mail with scheduled events. I just turned it on, so I can check the right time on my Jolla trough the mail.