In battlegrounds, after playing a Freedealing Gambler (and receiving 3 gold), I bought anotother card. Having 2 gold left, I tried to refresh the tavern. That didn’t work, resulting in the messsage ‘Not enough gold’.
I created a screenshot in case you’re interested.
Just guessing, but I think the gold coin graphic is probably showing you have two coins, but the coin counter is saying 0/10. There is an occasional bug with coins in BG (and mana in regular games) which causes the graphic display to show an erroneous amount of resources left. The number is always correct though.
Ah, you’re right. I didn’t notice the counter, it says 0/9 indeed