Sorry, this bug is fixed in the github version but not in the quicklisp version (darcs).

The bug was in utilities.lisp, function process-brackets with the variable buffer-count not being incremented

BTW: in order to load the github version I had to comment this line

#-asdf-system-connections :container-dynamic-classes

from cl-markdown.asd.

I don't know where this system is defined.

andy