Try using 10.5.8. This is working very consistently for me with Omnisphere. You might even try different text programs, both TextEdit and Word work when you type into a document and come back to Logic and type into the Save As window.
Thanks for sharing. I think you're suggesting the same method as Darren suggested on Page 2 of this thread? In which case, great minds think alike (and laterally!)
I'm gonna stick with saving as channel strips for the time being until Apple provide an update :)