If you think you found a bug please report it including steps to reproduce here https://github.com/openmediavault/openmediavault/issues
I'm not quite sure this is a bug. Perhaps this is a feature of my hardware or something else. I think it will be possible to consider that this is a bug, if this problem appears to someone other than me. At the moment, I think that the workaround described by me will suffice.