OK so BUG or NOT. Maybe I can help at least a few people solve their issue. I've been dealing with this problem for many weeks, and going back and forth with our IT dept. As of right now, I feel really stupid. I was having the exact problem which is described all through this thread, right from the start. I'd tried everything suggested to get it sorted out but to no avail.
In DEC I upgraded from iphone 4S running latest operating system to iPhone 6+. The calendar always synced right up just fine with the correct time zone on the iPHone 4S. I never had the calendar in question (my work calendar) on my ipad Air, but decided to get the work calendar going on both the iphone 6+ and the iPad Air. I followed all instructions to a T (or so I thought).
So here was my brain dead mistake. Numerous times I logged into Google Calendar
https://www.google.com/calendar
Each time I selected the settings wheel upper right page under the email address. Here I set the time zone, and then checked this again numerous times when I started having the GMT issue. So, in my mind, the time zone was set correctly in the Google Calendar web page. Everything was set correctly in my iPad, and Iphone 6+ settings. I found this thread and figured I had the same problem everyone else was having because it was identical to my issue.
So finally my IT guy, who has access to my calendar sends me a line by line instruction set, and tells me that my work calendar is set on GMT. How can this be? Again, I go into to Google Calendar from my desktop pc and check the setting - it's clearly set to Pacific Time. He says he's never heard of this Bug and others are not having any issues. So this time I go back and read his instructions again, and it says to go to the left side of the web page and work with the "MY Calendars" drop down menus there. Here, the calendar tagged with my name is set correctly to Pacific time, but the work calendar next one down on the list, is set to GMT.... I corrected this and now everything is as should be...
It isn't necessarily intuitive to open the Google Calendar web page, find the setting which allows you to make a time zone adjustment, then make this adjustment, and not be "done" with the time zone setting for the Google Calendar web page. I'm sure many of you are thinking well that's really stupid but at some level of user ability, this is exactly what happens, and it happened to me....
When I watched the utube video in this thread, I tried it with the same result. Now it's clear that the reason that it worked fine - creating a test event on the Google Calendar web page which synced correctly to all devices - didn't generate an incorrect GMT time because that test event creation was done on a calendar which was set correctly to Pacific time. It was my separate work calendar that had never been set correctly and was still set on the default GMT....
I hope I'm the only one on this thread who was too lame to follow instructions, and talked myself into the fact that I was sure I had some bug problem....
Hope Apple and everyone gets it worked out sooner or later..
Jack