The origins of the strike go back through decades of council mismanagement - would take a book to outline it. (Almost perpetually against legal advice). The general view is that the workers shouldn't be expected to carry the can for council mistakes.
Remember this is a council that managed to spend £100 million on an accounting system that can't produce an audit (and apparently never will) and that no one anywhere is going to get any blame for.
They are also incapable of putting a fucking SSL certificate on their crappy bespoke council website.