Default Portfolio suddenly showing USD instead of GBP

I've had a Coinbase Pro account for some weeks and have been slowly investing in ETH. I check my default portfolio from time to time to see how much it has gone up by (though mostly down recently).

I put money in as GBP and it has been showing me the value of my ETH in GBP up until today when it is now showing me the value in USD.

I was quite chuffed as I thought my value had skyrocketed.

I have tried changing my default currency in the settings of Coinbase.com but can't see any equivalent settings for Coinbase Pro.

Any ideas?