Error approving paper referenced by other assets

This appears to be a landing page, yes?

Did you unapprove it and then re-approve it?

You a probably referencing this page in a campaign flow step inside the Program or outside the Program. Look under Used by on the landing page to see what's going on.

I just cloned a program and ran into the same issue, but while trying to approve an email.

The assets within the program were already approved, but after I made edits and tried to reapprove I received the same validation error. Like Josh suggested above, I had to unapprove the email then reapprove. None of my edits were saved, but at least the validation error is not appearing now when I approve the draft.
 

Yeah, it's a landing page. Sorry for not specifying that before.

I just tried to unapprove and re-approve... no luck. I get the following:

An Error has Occurred
The details of this error have been sent automatically to Marketo.
Refresh your browser.

It is referenced in a campaign flow, but I removed the references earlier with no luck. The campaign items aren't active, either.

I didn't see a "Used by" area under the landing page. I checked another landing page as well, and that also doesn't show a "Used by" area. Am I missing something?

I've refreshed my browser several times, and even closed out that tab and opened a new one. Strangely, I can edit and approve all other pages except for that one. That's the only one that gives me any errors right now.