Same problem here 5 Ubuntu 16.04.3 LTS machines + One machine Win10, 2 networks. It only heppens on all Ubuntu machies after short time of internet down (router restart twice a day ISP setting). After that all Ubuntu machines are off in their networks. I have to restart manually hamachi service to make it visible in networks back, or sudo service hamachi logout then sudo service hamachi login.
Hamahi version on each Ubuntu machine : 2.1.0.174