The Decimal and Group settings for the UK region file (en-GB) are incorrect. They are set a:
numericDecimalSeparator: ',', numericGroupSeparator: '.', but they should be reversed:
numericDecimalSeparator: '.', numericGroupSeparator: ',',
Hello Karl,
Thank you for reporting this!
I created a development issue regarding this with number 142160.
You can monitor its progress through the support case CAS-116119-G3S0Z9.
Let me know if you need further assistance from my side.