I created a filter in SMP based on software inventory and when I named the filter I had a less than sign in the name (<) and this caused this filter and another filter with a similar name to not show in the list to apply to when building a managed software delivery policy. This caused a bit of frustrations for a few minutes (since the filter search sucks) untill I figured out what the issues was. I've tried a few other characters and the ones I tested worked fine ( "!,%,#,>" ).
Here's the filters I was trying to build:
Computers with Firefox installed - Already existed and showed up in filter picker.
Computers with Firefox < 19 installed - Caused both of these filters to not show up.