@RiO
Just because that seemed working well under 16.04 doesn't mean the android firmware was the good one and you shouldn't install recommanded required one.
Plus, it is recommanded to full install focal from ubports installer, not updating from xenial as it can lead to issues for now.
Last, Note 7 Pro is not already in supported focal device list (toggle filter to see focal devices in device list), so, knowing Focal is under heavy dev, and not fully stable on supported devices, don't expect it working well on yours.
Anyway, try to contact port contributor if you want to help improve port, you can find him on violet device page.