Imported Image and Layer Control

L.C. 2.1.2 on Lubuntu 18.04.2.
Generally works well and I am very pleased with it.

But, handling imported images on Layers is perplexing, and often frustrating.
Scaling and rotating seem unreliable, needing a couple of attempts to get the desired result.

The worst aspect happens when I make another layer and draw lines in the new layer.
The image often changes its Layer property and joins previous lines in previously allocated Layers.
Then, it is impossible to separate the lines from the image.

As I am trying to do parts drawings of an item only available as an assembled JPG image, many of the lines are drawn entirely within the image.

Not sure if this behaviour is a bug, or my lack of understanding.
Am I going about this the wrong way ?
Suggestions ?

John (in bushfire ravaged Sydney).

Just tried Locking the image Layer - that looks promising.
John.

There is a problem with scaling images, they seem to disappear. Auto Zoom brings them back. This has been fixed in 2.2.0 RC series.
I don't experience trouble with rotating. What exactly is happening - not working?
Layer trouble: buggy, yes. Properties always shows active layer. Switching layer visibility on - off shows true layer.
If you try to select an entity on an other layer by clicking on it, allways the image underneath is selected, or prevents the lines to be selected,even if it's layer is locked. You can select the lines by pulling up a window around them, not including the image. This is a bug.

Thanks Dellus,
I was aware of the scaling problem from previous discussions, I just "Auto Zoom" to cure.
The Layer Lock cures my frustrations with undesired layer property changing.

The interesting thing with scaling and rotation of images is the apparent low precision.
All aspects of drawing line control adjustments are impressive in comparison.

Scaling like "1087.23/1087.5" to adjust image size to a known value, rarely provides the correct result, and often goes the wrong way !
Rotating 0.05 degrees to align the image with the Grid often gives variable results also.
Probably reflects the difficulty of manipulating pixels in the image.

The correct result is obtained after a couple of iterations.
Not a big deal, easily corrected or made smaller than the drawing allowed tolerances.
John