Replacing the title tag in my theme didn't work either.
Specifically, the way WP SEO and Query Multiple Taxonomies rewrite titles don't play nicely together.
Or maybe neither of them played nicely with my own title rewriting.
Whatever. I really just wanted to disable Yoast's title rewriting.
There are a number of posts here with solutions that worked for some people, but none of them worked in this particular case, so I did it the dirty way. Just hacked it out.
Important Note: It is not normally good practice to change a plugin's core files.
Main reason is that you will have to repeat this step each time you update the plugin.
Anyway, here's the simple fix.
In your plugins folder, find /wordpress/seo/frontend/class-frontend.php
You can get this via FTP, or even just go to your wordpress backend plugin page and hit edit.
In that file, search for the wp_title filter.
The version I most recently had to hack had it on line 32, and it looked like this:
add_filter( 'wp_title', array( $this, 'title' ), 15, 3 );
I think an older version used to have different numbers toward the end of the line. It should be the only line that starts with add_filter and has wp_title in there.
Just add a couple of slashes in front of this line.
That identifies the line as a comment only, not to be executed.
It effectively stops the whole ugly thing in its tracks.
// add_filter( 'wp_title', array( $this, 'title' ), 15, 3 );
Of course, this will disable all the title functionality of the plugin, which might be another problem altogether.
But if you were happy with your titles before, this is the quickest way to get them back. Especially if the solutions in the other threads haven't worked.