Issue with Multi-Size Mosaic and Predefined CRS

Hi Everyone,
I am having an issue (seems a tupid bug in the SNAP code) when I run the Multi-Size Mosaic with a Predefined CRS. In particular, SNAP do not recognize my selection and show a message window saying " No 'Coordinate Reference System" selected " when actually I selected the epsg:3031.

Is there a different to report this annoying bug?