When clicking the cogwheel button I get the following:
"RemixCogwheel has been blocked from an action only available to the Blizzard UI.
You can disable this addon and reload the UI."

thats no fun. when I was writing this, navigating around some of this stuff was tricky, so no surprise there is variation. To help narrow down possible issue:

Which gem was it?
Do you have a custom list of cog gems you enabled or ordered in the settings, or just default?
You weren't in combat?
Anything else that might seem relevant to your character.