Here's a similar situation that still isn't fully resolved.
https://lemm.ee/comment/554535
https://vlemmy.net/comment/519346
I replied initially with a reply from my Mastodon account.... After a day or so it never appeared so I posted again. The person I'm replying to said he sees both posts (on vlemmy) while I still only see the post I made directly to lemm.ee and not the one from my mastodon account at opencoaster.net