No clue. If it helps at all, I have DrivePool v2.3.2.1493 on a Win10Pro box with a mix of nvme ssd and sata hdd, and I even plugged in a usb hdd to see if anything changed, and I'm not getting that issue.
Edit: spoke too soon. I am seeing that on the usb hdd I plugged in, but not my other devices. It at least involves the DrivePool service, as stopping the service stops the effect and starting the service starts it back up.