Not sure why it stopped working, but it looks like it did change route, since it was at a -105, not sure what the new signal strength is. Z-wave has logic built in that figures the best pattern to build stable meshes, and many times it will take routes we don't understand, due to environmental factors, radio wave reflections, and adsorption of surrounding materials, and many other factors.
If you can be patient, I'm sure Hubitat will have some z-wave improvements coming out.
In the meantime a great guide is here:
my network was pretty good and worked for years with smarthings.. i have replaced all zwave switches and light switches with zwave plus, also all motion and door and water are now zwave plus as is my water valve.. the only old zwave devices are now the garage door openers.