I can't say for sure this is RC3 but when my mover process kicks off, the WebUI becomes unresponsive as well as my SMB shares.  All my docker containers (docker image and appdata all stored on an unassinged SSD so completely separate from any disks involved in the mover process) become hung during the mover process as well.  I see the CPU usage (Xeon D-1541) at about 28-30% during the mover yet I have nothing else consuming CPU on the system during this mover process.  Both my BTRFS cache and my
Minor