Hi @Nemysys, this sounds like a bug in Plesk or in your configuration of it. I think you'll need to ask Plesk support because so far no Plesk developers are participating in this forum, and they are probably the only ones who can fix this.
If you're comfortable with command-line system administration, you could also try one of the other clients, since you have a dedicated server.
However, they would probably not integrate very cleanly with Plesk.