This is a manually installed OctoPrint on top of a full Buster install.
OctoPrint (NOT OctoPi) need to add "sudo apt install libatlas3-base" (included in OctoPi).
I don't know how you do that but cp2004 said it was noted in BedLevelVisualizer that this is required.
After installing the lib file - the install ran flawlessly.
This is a manually installed OctoPrint on top of a full Buster install. OctoPrint (NOT OctoPi) need to add "sudo apt install libatlas3-base" (included in OctoPi). I don't know how you do that but cp2004 said it was noted in BedLevelVisualizer that this is required. After installing the lib file - the install ran flawlessly.