@David.P; Just to check, you are Saving the file first, before Alt-Tabbing back to the Web form?
I should add, TEA fails to transfer text one way or the other for me fairly frequently, but I can't get a handle on it. If it doesn't transfer text back the the Web form, I often add a space, backspace over it again - so the editor thinks the file's been changed - re-save it, and usually the next Alt-Tab back again transfers the text.
It seems to work better with some forums than others. DC works well. Fountain Pen Network, not so well.