welcome to winmxworld,
you say you share 37,000 files and add more all the time,
the possible problem is,
if you're on primary connection, winmx only allows 5,000 files to be shown, the rest are not seen by anyone,
if you're on secondary connection, that limit is reduced to just 3,000 files,
its the way it is in the making of winmx, we can not change it,
it is possible its too many files for winmx to index, that could be why its ignoring your folders.