P: After soft proofing: before/after [shortcuts / and Y] do not show correct before/after (non-Raw)

Hi there!
The subject says it all. After I soft proof an image for printing I can't usw the before/after shortcut anymore. It seems like the "before version" is just gone. That's super annoying. 

I  uncheck soft proofing, hit the shortcut and nothing happens. If I don't soft prrof lightroom would show me the before image with zero changed values. That's what I need. 

Please help or fix this. 

Thanks!