Hi @scott2 & @colin.baxter ,
This is in fact a bug in the media library at the moment. We've discussed it previously here:
As you can see the search doesn't work consistently:
https://www.loom.com/share/72c9dcb310cc4e2aa06fa61d92f01966
We plan on doing maintenance to the media library in the future because of this issue and I can only apologise for the inconvenience this is causing in the time being. We will update everyone in the above thread if/when there is any update on this.
Right now the best workaround is to add keywords in the 'private notes' section which will work as tags.
Thanks.