I can't say more
I can only encourage You to do more tests and think more if Your computers have something special that may affect this problem.
- I also forgot to ask you which are the hardware charactersitics of yours (processor, ram memory, antiquity of them).
- If You say that You have 2 computers with Ubuntu 16.04, and both have the problem, my main suspect is then Ubuntu 16.04. I think You should warn and request help in the Ubuntu bug system, in developers mailing list or user forum.
- I haven't seen nothing related in Inkscape launchpad, but You may prefer do other search:
https://bugs.launchpad.net/inkscape?fie ... o_package=- Have You seen this kind of behaviour on other programs, like GIMP?, or perhaps any other graphic editor on the new Ubuntu?
- If You have the chance, try to install a Previous Ubuntu in one of your computers. As I said before, In my system that feature works as expected.