Being a councillor is a privilege and, as with all privileges, carries responsibility. Councils conduct their business at meetings, to which councillors are summoned (not invited). If you're not at the meeting, you're not participating in the business of the council, for which you were elected or coopted. In order to perform their function effectively, members should make themselves aware of the framework within which they operate, for which a new councillor training course is a good starting point. This should include the significance of S85.
In my days as Chairman of my parish council, I started reminding members of their responsibilities long before S85 came into play. Anybody who missed two meetings without good reason was challenged to demonstrate their commitment to the role. This is not a prescribed route, but it's one way to focus the mind.
Having said all of this, in my opinion, the buck stops with the Clerk, as the legal and financial officer of the council, as this is a legal matter, so if the Chair hasn't stepped up to the plate, it is incumbent upon the Clerk to avoid the embarrassment for the individual of announcing this at a public meeting.