I know that I can use "Show search option" to find items that have both tag-a and tag-b, but it's not so convenient.
Perhaps you can make it so I can select two (or more) tags on the left column (where all the tags are listed) (e.g. cmd-select on Mac), to show items with "tag-a"-AND-"tag-b".
1Password Version: 6.6.BETA-4
Extension Version: 10.12.2
OS Version: 4.6.2
Sync Type: Dropbox