I just upgraded to Insync 126.96.36.199421 from 1.5 .
Initial sync using the same old folder did work , apart some errorß similar to (error doing ModifyCloudReg) that I solved deleting the few files.
Now I have two main machines with Max OSX Sierra 10.12.6, both can sync to GDrive , but the files from machine_1 are not copied over machine_2 and vice versa.
In GDrive I can see both file uploaded.
EDIT : I tested now that files adde to GDrive web interface do not appear on any machine, it seems that sync from GDrive isn’t working, but pushing files is fine.