Search Builder operator != not working for tags or groups

When using the search builder, if you try to select all contacts that have one tag and are not tagged with a second, the second part of the query is not working. The results are the same as just selecting all contacts with the first tag.

Tested on the sandbox.

Here are the steps:

• Add tag 4 and 5 to a contact
• Search Builder
• Individuals | Tags | = | 5
• Results in 24 records
• Click "Another search field"
• Add Individuals | Tags | != | 4
• Search results in 24 records

• Add group 2 and 4 to a contact
• Search Builder
• Individuals | Groups | = | 2
• Results in 23 records
• Click "Another search field"
• Add Individuals | Tags | != | 4
• Search results in 23 records

For each of these I expected the results to be less, removing contacts that had the second group or tag.

Thanks,
Colin