Why has sorting (and filters) stopped working?

I’m using Dawn 2.0 and haven’t made any recent changes but I’ve just noticed that the filters and sorting on collection pages no longer works.

In customization, under ‘learn more’, I’m getting a new message to say that filters won’t work on my theme - even though that was not an issue when I added them and Shopify documentation states that filtering will work for any 2.0 theme (using Shopify Search and Discovery App).

Shopify support wants me to update to latest version before they will tell me if it’s update related. I don’t want to do a rush update at this very moment…I’d be happy to just have the SORT option working in the short term. That’s a basic function that should work for any version, no?

I’d really appreciate any ideas.

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