If the Clip in a Clip is positioned anywhere except x=0 and y=0, it draws as desired. When the Clip in a Clip is positioned at x=0 and y=0, the merge of the outer Clip extent with the inner Clip extent creates an extent region with these values:
X0 = 0, Y0 = 0
X1 = 0, Y1 = 0
This is used by the Clip object to represent an empty extent. Because this is used by the Clip object to represent an empty extent, the Clip will never draw if it is positioned exactly at 0,0 and its width is 1 pixel and its height is 1 pixel.
The workaround is to move the Clip anywhere else on the screen, event just something like y =1 and x =0. Then it will always draw (in this case, it will draw the single red dot as expected). Also, it will draw if it is positioned at 0,0 and it has more to show than just 1 pixel.
Altia will not make any changes to this behavior. This is a use case that is easy for a workaround. There does not seem to be a reason to have the Clip positioned at 0,0 and showing only 1 pixel.