I think I know why, the index table automatically removes some special characters, including the ‘+’ sign. I can make a modification to allow that, but unfortunately I was not able to log-in via FTP (I also tried SFTP). Can you please check the details and let me know if I need a special configuration?
Thank you!
I am sorry, I forgot to follow up. If you update to the recent release (4.13.1) and re-create the index table, then it should be resolved.
I have made a minor change within the current release to allow more special characters to be indexed.