Rounded corners BG issues with TIFF and swop colour space

I am using 1.45 (1024) and having a problem with the Rounded Corners effect when opening TIFF images that have a US Web Coated SWOP colour space. The opacity sliders don’t seem to be working the way that I think they should.

This shouldn’t give me a red BG.

And this shouldn’t give me a white BG.

When I convert to SRGB (either in Retrobatch or via Acorn) the effect works fine.

Is this the expected behaviour based on the colour space?

US Web Coated SWOP profile images don’t have an alpha channel (since it’s CMYK). So, the opacity isn’t going to work in this case. Converting it to RGB(A) will do it though.

Technically, yes - a CMYK image saved as a TIFF file (or PSD) can have an extra channel that will serve as a mask. However, Retrobatch is probably only ever going to work with four channels for the images, since things get real ugly real quick when you step out of that range.

I added a convert step and everything was fine.

Perhaps adding an alert for users when they try to do something like this?