We had several missunderstandings here
not sure about other's but for us X then X and then 3♦ cannot be a pure 1 suiter, it is normally 1453 but 1363 or 0463 are possible.
south though 3♠ showed hald a stopper in spades while norht took it as a good diamond raise, maybe ♦Qxxx ♣Kxxx
north bid 4♠ as a COG, but south understood it as a void or something very very strong.
Both players agreed that 3♣ was an underbid and started the mess

Help

(1♠)-X-(ps)-2♣
(2♠)-X-(ps)-3♣
(ps)-3♦-(ps)-3♠
(ps)-4♠-(ps)-6♣
(ps)-(ps)-(ps)