Sync : problem with imported documents

Hi, as I didn’t found any solution yet, I’m hoping somebody has an idea…

What I’m trying to do

Syncing (via obsidian sync) an imported document (.md document placed in vault) from machine A to my other machines/obsidian installations.

When placing an .md document in machine A’s vault, the document is imported into the vault and visible (on machine A) (=working).
From time to time, obsidian on Machine A shows „indexing of document… takes some time“ for the imported document.
On the other obsidian installations (all synced via obsidian sync), this document ist NOT visible (even after waiting hours).
When placing an .md document in another machines vault, the document is synced to all other obsidian installations.

→ obviously, this is a problem on machine A (Windows 11), but only „one way“ (from machines vault into obsidian sync). Other way around (from obsidian sync into local vault works.)

I tried to uninstall and reinstall obsidian: same behavior.
Windows 11: latest version/latest patched, obsidian: latest version

Does anybody have any idea ?
Should be glad for any hint …
thanks a lot,
Marcel

This happens with any file on that device? It’s not a particular file that’s unusually large or something?