Bug with update link from the “Network Admin – Settings – User Role Editor” form was confirmed and fixed. Please try updated version 4.17.b3.
When URE is activated for single site (not network wide) its settings (single site Settings – User Role Editor) are applied to that single site only, including the “Multisite” tab options. It is named “Multisite” as these options have sense for the multisite WordPress installation only. You will not see this tab at the single site WordPress installation.
So, Yes, it is supposed to be on all sites where URE is activated.

Thanks for your help. I wait results of tests with 4.17.b3.