iTunes match deleting playlists prefixed with an underscore?

I noticed this morning I was missing my "radio" playlists including the folder that contained them. The folder was named "_Ben network" and the playlists were named "_Radio NPR", "_Radio Ben", etc. After doing some checks with a previous backup, it seems to be just these playlists and curiously, if I connect to a network after restoring my iTunes library from a backup, those playlists become removed again! I have re-created these playlists in the meantime and it seems to work however I'm nervous about it deleting these playlists again. Anyone else have this issue?