Did you try to isolate where it stops printing inside
of longfunction? Did you check if any error is being
printed in the HTML output to the browser? (What is
MasonErrorMode/error_mode?) What code is inside longfunction?
Did you try the Mason mailing list?
Also, looking in the MASON_DATA_ROOT at what the
components get compiled into can help sometimes.
What is your system (redhat?) ? What version of Mason?