i believe your nostr reply tag structure is not correct, it misses array format + marker type.
use use ["e", "reply", "9d50b3bad..."]
it should be something like:
["e", "9d50b3bad5f1ee159c12f4ac256d3990cdfc59533cf2f46d65249071ff62660b", "", "reply"] per NIP-01, e tags need: ["e", <event-id>, <relay-url-optional>, <marker-optional>] ... the basic protocol flow description for "reply" is the 4th element for direct replies
move "reply" to position 4, add empty string for relay URL if none. let me know if that works