I'm not sure.
Yes, I also switched to the Apex Listener,
but I was able to reproduce the problem using the EPG listener on port 8080.
I don't remember whether I was able to reproduce the problem on apex.oracle.com though.
I removed the initcap in the dynamic action, and the character was correct.
What you could see was when the page was loading, initially the character was correct, and then initcap bumped in.
I corrected the character using sql*plus, queried the record again and ... gone.
I saw the other thread though, and the problem does look similar, but it seems there is something more generic going on.
I now am in the process to convert this database to AL32UTF8, one never knows (currently it is WE8MSWIN1252).