learning by doing is the way! happy you claimed the ecash
yeah I think it was probably because the first mint sent you ecash denominated in USD and the mint you had on nutstash was only accepting ecash denominated in sats.
keep learning, if you got more ecash question don't hesitate to tag me. This kitty loves nuts.
please remember the protocol and wallets are still very new, do not use ecash for large amounts or cold storage.