I log into my Plex server via Safari on MacOS 10.14 Mojave.
I go to Settings > Manage > Live TV and DVR. I see my DVR, an HDHomeRun PRIME, listed there.
I click the gear icon to edit its channel listings. The channel list box pops up, where I can theoretically enable or disable channels.
But on Safari, while I can scroll up or down through the list, none of the buttons work. The whole screen stops responding, save for moving through the list, and I have to reload the page to return to normal.
When using Chrome on the same Mac, I can adjust those settings just fine.
Server Version#: 1.13.9.5439
Player Version#: 3.73.1 (web)