I have a good suspicion that this is a user error. This solution works for 1000 out of 1000 people Or what is your wish? Do you want 1 cm thick roads? Find it in the plugin and edit it for yourself.

default.vis > [ROADSTYLEPARAMS] Rewrite all values from 0 to 28 to a higher value as you like. The default.vis file is in two places, both must be the same.

Good game, you can play with it for a while