Issue Discovered With The EOS 5D Mark IV, Firmware Fix Coming

[Maximilian]

You need to turn on the daylight time symbol in the Date/Time/Zone menu in the camera. It looks like a Sun symbol. Just setting the time ahead 1 hour is not the same thing.

Yup, after updating to the latest version of EOS Utility (I was on 3.7, and 3.8 came out in February) and having the problem again, I just noticed the box to the left of the time zone, and wondered what it was for. DST right there.

User error.

Good that you found the solution. I suppose it is the same as I mentioned before:

I also assume that you have the summer / winter time switch in the right position.

Another way would have been to deactivate time sync in EOS utility.
But if it works now, that's fine