Tried to play 2 games just now. With Lord Rat.
Game 1. Had 3 coins on my first turn. BUT, was not allowed to buy any of the usual cards, and was given the option only of buying: Copper, Curse, and Donate. I resigned.
Game 2. Same issue. Started with 4 coins, but could only buy: Copper, Curse, and (I think) Blacksmith.
No point in playing this type of game, obviously. I'll check back here tomorrow, to see if anyone knows the issue, or what the problem might be.