VBA attached to button no longer works on external shared sheet

VBA attached to button no longer works on external shared sheet

Hi - we have a Sheet that our clients use, which requires them to press a button once they've entered data.

The button then triggers a flow via a webhook.

The button works fine when editing within Zoho Sheet - however when shared externally it no longer works (it has been working fine up to today).  The button just doesn't do anything when clicked. It doesn't trigger flow, it doesn't execute any VBA.  This suddenly stopped working overnight from what I can tell.

I was wondering whether this was just a temporary thing or whether Zoho Sheet have changed something behind the scenes?  Can I do anything to get it to work again, or just wait it out?  It's mission critical so keen to get it up and running again ASAP.

Thanks!