Running 3.23 !! Mentioned in the footer of the post.
I know I need to upgrade to .24 but that’s always a heck of a work.
Remember…
No, there is nothin there.
I know they are in quadrant 4 near the origin.
Somewhat @ 0.3,-0.1
Pointing and selecting in the void there is nothing selected.
Snapping to, nothing but the grid.
‘draw’ select excluding the origin. Nothing
Can add whatever I want as normal.
Can delete this again.
Can undo this, can undo the tool transaction.
Can FlexPaint what uses Addline too.
Select All
or Select Layers Entities
or ‘draw’ select including the origin
or simply ‘draw’ select a tiny area around the origin itself, eg. 0.01 by 0.01. 
=>
All 4533.
But only Start- and Endpoint indicators.
No line segments.
All listed in Prop Editor.
Can set common General Props with no result.
All specific Props are obviously VARIES
Except Total Lenght = NaN 
Except Angle = 0
This behaviour is know to me as ‘Null-entities’.
Save & Reverting, all fine.
Strange???
Will come back on this after wiping Qcad.
Thanks,
Regards.