I reported this two years ago and it STILL hasn't been addressed. That thread is locked now, so I'm raising the issue again here.
Select a couple of items in your library and apply a tag to them, say "newtag". Click in the Library filter box and type mytag:newtag. You can't finish typing it because as soon as you've typed a few letters (I got as far as mytag), the library catalog starts updating to take into account your new tag change, and the focus disappears from the box you were typing in.
This drives me nuts and prevents me from really using Logos to its full potential. It's so annoying to tag my library because of this glitch that I've gotten way behind on tagging my new resources and have virtually given up on ever catching up. PLEASE fix this!
Here's a video to illustrate what I'm talking about: http://www.screencast.com/t/Zk6CQ2Xlq