Some emails won't archive (unless I log into a different machine and sync)

Hi, I'm encountering an issue trying to archive all of my emails to the vault. Most of them will archive, but there's sometimes a few that refuse to archive. If I go into Outlook on another machine and sync it will work, but then a week later this issue pops up again. Anyone ever encounter this? Could this be an Outlook issue? I removed the vault plugin and then reinstalled it too, didn't fix the issue.