Problem configuring/using custom attribute in Halion

In an attempt to keep track of contenders when auditioning sounds I added a custom Y/N user field in Media Bay called Flagged. The idea being that when auditioning I could set the flag on potential keepers. This is working fine.

But I also want to be able to filter the results afterwards so I only see the presets where Flagged is set to yes. But I don’t see how to do this. Setting the results so it shows the field was easy enough. But when trying to configure the filters, not only is my field not listed - the majority of the other attributes are also not available.

Any ideas on how to make this work are appreciated.