Cut & Paste into Sketch from Drawing

I have a dwg file with various sketches on different layers.

I simplified the file to a level that I required. I then wanted to import the file into a part for modeling but I wanted each layer to be a separate sketch so, I imported the file into a SW drawing. I then turned off the layers that I did not want,  selected the entities I did want, switched to the part selected the plane and pasted the entities -  great.

However after working on the file I've noticed that the sketches contain the hatch pattern from the original file, they're  not visible, only identified by the fact that the cursor gets the hatch icon when over the hatch - which is not always in an enclosed boudary..

The hatch was on a separate layer to all the entities I wanted and it was turned off (could not see any hatch patterns when making my selection). I've systematically gone through the sketches to remove the hatch. This had quite an effect on file size.

Is this a bug?

Has anyone else seen this happening?

Is it possible to get the system to display the hatch and filter it so that it can be easily deleted?

This is not a regular operation for me so an ER would not really be in order.

I thought there used to be function that copied entities from a drawing into a sketch (way back). Has this been dropped/superceded by cut & paste?

SolidworksSketching