Just wanted to throw this out there for people.
Normally SWE doesn't let you insert an image that is not a .bmp (which is completely dumb) so i have been saving images as png or jpeg and then converting them to bmp in windows paint.
It will let you "attach" any type of image, but then if the image moves from the location you get an error displaying the image.
Well almost as a joke i just renamed the extension of a png to bmp in windows explorer and tried to insert it.
Well lo and behold it worked.
Im using windows10 and SWE19.4
So basically it means that all the program is looking for is the extension of the file to be bmp. (I can't believe that windows would do the conversion for me when I renamed the file)
TLDR;
Just rename your png and jpeg images to bmp and insert away.