My card did not automatically convert EURO to GBP

My revolut card registered in UK was topped up in GBP. This balance was later converted to EURO’s, I tried to spend in GBP ( account had only euros ) to check if it automatically converted EURO to GBP - this transaction failed. Any idea why

Hmm it should take from your available currency, have you reached out on support chat so we can take a look into why this declined?