I've noticed that on both Apple TV and MacOS.
Whenever I watch live stream eg. Science for longer time than single episode the displayed EPG on player are from the show I started. Looks like player not checking about what is currently airing live periodically, which is confusing.
Not totally following you. Are you referring to the quick guide that appears when you click or swipe down?
It might be a regression. There was a bug with the guide not refreshing while playing live TV, but had been fixed in the past. It was noticeable that when pulling down the Quick Guide, programs would no longer have information, and only the channel logo would display.
It is difficult to swipe down on Mac 
I assume you never used web interface, I mean the guide data that appear in player to see what is currently played on.
I'm talking about the grid guide in Channels. I use Nvidia Shields as the Channels client for watching TV and scheduling recordings. The DVR engine is installed on a separate Windows 10 HTPC. I access the guide from the list of options displayed on the left side of the screen (On Now, Guide, Recordings, Library, etc.). From there I search through the guide to schedule my recordings, but the day and time shown at the top of each column in the guide don't match the current day and time.
I just checked the guide again and it changed from Tuesday at 4:30 pm to Monday at 5:30 am for the same shows. I selected the option to download the entire guide again on the Windows 10 HTPC and this is what I got. The day and time were off prior to doing this.
You’re right about that, I never use the web interface to watch anything.