As the title describes, I've been forced into ground STFs several times in the past week even though I explicitly queued up for the space STFs. This was terrible for me and the people I got stuck with, since my Borg ground gear was in the bank both times.
Apparently the filters in the PvE queue only change the displayed text for each mission slot, but not what the actual missions in the slots are for. For example, if the 2nd slot in the unfiltered mission list is a ground mission, but you filter out ground, and then select the space mission in that 2nd slot, you will actually end up queuing for that original ground mission instead, even though it appears that you are queuing for a space mission on screen.
The filters are therefore only good for viewing the missions, but not for actually queuing them, because there's no telling what mission you'll end up in with the filtered view.