So awesome that Menagerie is finally available! I'm having a blast.
In my game #37175439, I played Wayfarer and although it said "You may gain a silver", only "Don't gain" was available. (See image.)
I didn't see any effect that could prevent gaining a Silver; that pile was not empty and the opponent had not played some sort of attack (though even under those cirucmstances I probably still should have had the option).
Unfortunately, earlier in the game, Silver-gaining was possible with the card, so I'm not sure how to replicate this.
Thank you for attention to this, and I understand if any bug-fixing is delayed for now..