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Try not work with jackdbus from qjacktl: turn off Setup/Misc/Other/Enable JACK D-Bus interface; killall jackd that might be possibly running; killall jackdbus as well; start qjackctl and try now again.

Also look for some error our suspicious evidences on the messages window

One question though: where did you get that newer qjackctl v0.4.5 from? Is that from regular ubuntu16.04 universe?
byee