Your setup’s behaviour is very confusing for me too.
On my Pi I dont get mlat failure when I install mlat package from github, and get mlat failure when I install mlat from rb24 (by apt-get install command).
The output of various commands you have posted shows that you have installed the package built by me, but you also reported that mlat fails when rbfeeder is restarted, which is the behaviour of rb24 supplied mlat-client.
Please be patient. Let me perform some more tests tonight or tomorrow to find out why me and you are getting diagonally opposite results.
Meanwhile you may brows this post.