That’s a LaTeX issue - not a MMD issue. Or more precisely, MMD displays whatever output your LaTeX program (pdflatex, xelatex, etc) displays. MMD is really just a series of shell scripts and pipes, after all.
This is actually entirely a Scrivener issue. For obvious reasons, MMD knows nothing about “importing” a MMD document. There’s no such thing. And this is entirely separate from exporting MMD into LaTeX.