Face of org-mode source block changes when returning from edit buffer

Question

A strange thing happens when editing source blocks within an extra buffer with C-c ': the face of just this source block changes upon returning, i.e. the face settings are not used any more.

I'm using Emacs 25.1 with org-mode 8.2.10.

What could be causing this?

Answer 1

I was able to remedy this issue simply through upgrading org-mode to version 9.0.3. So there's probably a bug in 8.2.10.