Dragging multiple items to a tag in the tag selector doesn't work when... the tag still doesn't exist.
This is a frequent scenario in my workflow, as sometimes I create a new tag which is not a "topic", but an "identifier" (e.g., "project X - week 3"). My workaround has been (1) creating the new tag in one item, then (2) selecting all other items and dragging them.
https://www.zotero.org/support/collections_and_tags#adding_tags_to_items
This is a frequent scenario in my workflow, as sometimes I create a new tag which is not a "topic", but an "identifier" (e.g., "project X - week 3"). My workaround has been (1) creating the new tag in one item, then (2) selecting all other items and dragging them.
But yes, we're aware of this limitation and will offer a way to create a new tag on multiple items in a future version.