Start Writer, insert a custom shape, e.g. "Diamond". Toggle Extrusion on. That icon is in the 'Drawing' toolbar. Select the shape. Go to File > Export..., choose jpg or png. Make sure 'Selection' is checked. Enter file name and save. Now you should get the 'JPG Options' or 'PNG Options' dialog. Notice, that the width and height fields have zero. Expected: The fields are filled with the current size of the drawing.
I confirm it with Version: 7.0.0.0.alpha0+ (x64) Build ID: c63148ba139bd6b9ae7a0f9e24e51f29e5370963 CPU threads: 4; OS: Windows 10.0 Build 18363; UI render: Skia/Raster; VCL: win; Locale: de-DE (de_DE); UI-Language: en-GB Calc: threaded