Hi 
Sorry you have not had any responses so far. Hopefully someone might be
able to help in a while. Sometimes it is a good idea to "bump the thread"
(which my reply here will do) in order to get your question back to the top
of the mailing list.
I have no idea why that sort of quirkiness happens. I tend to use
copy&paste to fill find/replace boxes because i have often found that all
sorts of different systems seem to have odd such quirks.
It might depend on the platform (Windows, Mac, Linux) or even the specific
OS (Xp, Win10, iOS(?), Ubuntu, Mint, Mageia) so please feel free to give us
a clue if reasonably easy to do so.
Good luck and regards from
Tom 