I agree - I'm guessing it's probably present in Ubuntu as well. I've had issues with anything installed via Flatpak/Snap.
While Evolution is bundled in with the Zorin install, it is the Flatpak version.
In the past, what I've experienced are sandboxing/permissions issues with anything from Flatpak or Snap.
Example - the Flatpak version of Firefox will not download anywhere but the ~/Downloads folder. Try to switch it to another location, it doesn't have permission to do so.
I've used Flatseal to overcome most of these sorts of issues, but I'm stumped on this one.
I've had issues with Zorin not working with some of my hardware, which are not present in other distros.
As much as I like Zorin - I recommend it to anyone interested in trying a Linux distro - sadly, I feel at this juncture it's time for me to move on to something different as a daily driver.
Zorin is incredibly easy to install and configure, and 99% of what I need is present and works out of the box. It's that last 1% that's a sticking point.
When I find another distro that gives me 100% - and it looks like Debian may be the one - it's time to move on.