iphone no longer recognises contact numbers beginning +44 (0)

Since updating to iOS15.2.1 I am unable to call any of my contacts from their contact card. The number dials and disconnects immediately. I have tried Dial Assist on and off and it makes no difference. All my contact numbers are formatted to start +44 (0), a format that is enabled by the Contacts app itself. If I edit the number to remove the (0), the number dials correctly. I have hundreds of numbers. Is this a bug that will be addressed, or should I undertake removing the (0) from all my contacts numbers?