Sorry I misunderstood Daniel,
You’re saying that your theme is already outputting og:description, but activating my plugin causes it to become empty?
Clearly my plug-in is conflicting with something you already have setup on your WordPress instance, but it would be too difficult to troubleshoot in a forum.
I wouldn’t call this a critical bug, but rather just another run-of-the-mill conflict we WordPress users have to contend with on occasion. Deactivate my plug-in and no harm no foul. If it was actually permanently destroying data (which my plug-in actually can’t do because it only reads from the db to get the open graph properties), that would be critical.
If I had a working duplicate of your website on my local development server I’d at least take a look to see if there’s anything obvious I could to to rectify it for you, but short of that honestly I would suggest trying a different plug-in if you have reason to believe mine is causing the issue. I know there are others out there that handle open graph properties (maybe way better than mine too), and perhaps they are more forgiving with your theme/plugin set-up.
I know it’s not the answer you were looking for, but good luck all the same.