Has something changed with preview above / below since 0.5.0?

My thconfig files that used to produce grey outline now produce nothing. I've gone back to my original sources from September, and re-built them using the current snapshot only to find that nothing is produced. See attached.

The pdf files were created using the thconfig file attached. I've also included my main source file, UpperFlood.th, which defines the map Outline_m2500 containing the preview above and below commands.

I've always found the description of preview above / below very difficult to understand in The Book. For example, I've found that I have to put a scrap reference into map Outline_m2500 before the preview above command, otherwise I get the error "incompatible map projection".

Any help appreciated.

Regards,

- Ben