Not able to run in Debian Testing

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Hello,

I have run the v1.2.0 RC5 Appimage for Linux on latest Ubuntu 18.04 Bionic and it works flawlessly at first attempt. It's impressive.

Hoewever, I have tried it in Debian Testing (up to date as of may 27, 2018) on two different machines, one with LXDE and the other with GNOME. In both cases it shows the splash screen, then exits with the error

/tmp/.mount_lmms-1hv8JSM/usr/bin/lmms.real: symbol lookup error: /tmp/.mount_lmms-1hv8JSM/usr/lib/libportaudio.so.2: undefined symbol: jack_client_open

So the whole point of the self contained appimage seems not to be (yet) there in this case.

Any ideas? Thank you.
This is a regression in rc5 and should have been fixed in rc6 which was released just a day ago.
https://lmms.io/download/#linux