Exporting IS TERRIBLE
I have used photoshop for many many years - your new updates are terrible. I've started to switch to sketch for almost everything since after I work on a file I cant export them properly... I am trying to export a png. what it SHOULD do is export the same size as the artboard. HOWEVER it decides that not only does it not need to export the size of the artboard, but it has a white background (which is NOT in my file).
I am an expert photoshop user - but since you guys have starting making crazy weird updates with bad usability I've started using it as minimally as possible... Shame...