Any canvas set with transparent background is white and exports as white

A vetran of Fireworks, Photoshop for many many years however just recently i seem to have done something that makes any canvas i set to the transparent colour turn white and when exporting in full png format the image has a white background, its as if the FFFFFF00 colour code has been replaced with FFFFFF making the software pretty useless now and i cant work out if its me or an issue with the software.

If anyone has found this or has any pointers to fix this id appreciate pointers 🙂