"the current time on this device seems to be incorrect". Can't purchase from Apple Online Store

I'm trying to order a Calendar but this error keeps coming up.

I've done this before so can't understand why it's happening now.

I live in Malta so under Photos > Preferences I chose 'United Kingdom' as there's no option for Malta.

My Apple ID shipping address is set to the UK too (since it doesn't deliver to MT)

My Apple ID billing address is however, Malta, and my Date & Time (System Preferences) is set for Malta.

What should I change so that I can be allowed to order???