Lemmy only has limited support for mastodon, so unless they tag a threadiverse community in their post it won't reach a Lemmy instance. Mbin and since recently also Piefed have better support for mastodon

that explains why we haven't hear from them in a long time. lol

Instances don't "sync" with each other. When you make a post, it gets sent to a list of recipients. If your instance has someone on that list, you get the post. If it isn't, you don't. Which isn't really what I understand as syncing, and it sounds like it's not what you expected either.

The list of recipients usually includes the person you're replying to, any people you mention in the post, and all your followers. On Lemmy, it includes the community you're posting to, which then shares the post with all of its followers (subscribers).

But Lemmy users cannot follow other users, they can only subscribe to communities. And Mastodon users don't tend to use communities. This means that the ways in which your instance can realistically receive a post are very limited:

• it mentions someone from your instance
• it's a rare Mastodon post to a community (or reply to a Lemmy user)
• an Mbin community captured the post via its hashtags and someone on your instance is subscribed to that community

If you want to properly interact with Mastodon, I recommend switching to either Piefed or Mbin. Both of them are similar to Lemmy, but support following users, avoiding this issue.

Thank you for the explanation. I just wondered the technical limitation and the reason. I dont need to use Piefed or Mbin

I understand. thank you for the explanation.