I use ON16 on a day-to-day basis, but keep checking back on the ONW10 version. When I went in today, I found the tag search was available. However, I found it still falls short.
The search appears to based on the label for the tag. For example, if you use the out-of-the-box tag “Critical” (!), you have to enter “critical” in the search box. So, you can search for custom tags but you do it by the tag label, not from a drop down of available tags.
The implication here is that ONW10 does not differentiate between a box that is checked versus non-checked.