No idea, I can do that in the communities I moderate: (edit: you cant do that directly in the modlog. Apologies. you have to access the deleted post and restore it like this:)

Photon UI:

Standard UI:

Generally you can’t. You can see the truncated comments in the modlog itself, but not the posts. You can try to find an instance that doesn’t yet deleted your post (it takes some time to propogate to all instances), but it’s a witch hunt.

That looks like the error that shows up when the community hasn’t synced with the instance yet, usually when you’re the first to subscribe to it. My guess is that the removed post wasn’t synced to your instance before it was removed, so your instance doesn’t have a local copy to show you. You could probably get around this by navigating directly to this community and then checking the home instance’s mod log.

Here’s a direct link to test it out: https://lemmy.ml/modlog/8

Note: I’m guessing as I don’t have access to server logs to confirm.