It has been identified the 'Or is blank' option has been removed from yes/no filters in Query. The example given is within Revenue attributes; "Gift Registry banking form". Selecting the value for the filter, the only filter which can be chosen here is "is equal to"; without the option for "or is blank" it is not possible to filter for items that are not equal to "yes". This is a problem for attributes which are sometimes blank. I believe this option was previously available within v2.1 and was removed in v2.5. It doesn't appear in 2.7; are there any plans to bring it back?