Hi there!
I encountered exactly the same problem with both installations of c::b 16.01 and 17.12, regardless of wx2.x/wx3.x on a Win 10 subsystem for Linux Ubuntu installation (Bionic ver). It seemed completely random which files c::b displayed or not. All files I've tested are completely equal in terms of encoding, permissions, etc. and fully visible in other editors (vi, emacs, gedit, etc) so the discovery of the file size < 617B issue by tianrenli92 really saved my day, and probably the coming week!!! Thank you!!!
The quick fix is of course just to add a few # signs in the files smaller than 617B, but a bug-fix is probably appreciated

What is the latest news about this issue? Could not find anything about it elsewhere...