Failure of returning pictures edited in Affinity to Photos library

[Fred Luskin]

This started happening  Mojave and continues in Catalina. I wanted to straighten a picture but didn't want to lose data on the margins so I enlarged the canvas and then used the format tool to straighten the picture, Applied the straightening then used the Inpainting tool to fill in the blank margins (quite successfully). When I went to Save the picture (Command S) After the timing bar completed its journey across the message appeared that the operation could not be completed  and to try again at another time.

[markw]

Hello Luskin,
Hate to be the bearer of bad news but this is a well known bug that has yet to have a fix.
At the moment if you are on Catalina there is no way to round trip an image from Apple Photos to Affinity Photo and back.
Some users here on the forums have found an app on the App Store called ‘External Editors for Photos’ to use as a temporary stop gap for now to get around this problem. But it might not suit everyone's workflow.