Why does code disappear when in Code block macro?

[WW]

Running Confluence Data Center v7.13.2 (and some plugins, so who knows if they have anything to do with this)

Created a Code block macro and left the default settings.

Inside the macro body I put:

c:

When I preview or update and view the page, the code block is blank but has a border, so I can tell where it is.

When I edit the macro's settings and refresh to Preview, it flashes c:, then disappears.

I have another Code block macro on the page with more code in it, and it appears fine.

I tried using the No format macro, but for some odd reason, the panel is not appearing, even when the No panel checkbox is unchecked (and when it's checked).

Something screwy is going on, anybody know why?

[Bill Rudy]

I've had a similar problem (Confluence Server 7.19.1)...several times recently code just disappears within a code block (the macro shell is still there). Oddly, I have another code block on the same page and it didn't happen to that one. Definite bug. 

[Brant Schroeder]

@WW 

Have you tried clearing your cache?  Could this be an upgrade break?  Have you tried restarting Confluence?