The problem I have, is that .* isn't matching across lines, or rather (?mi) or (?m) isn't making .* match across lines.
Eg, it won't even match
(?m)\nOrder your copy
ie it doesn't like the \n on one line, then Order on the next, yet it matches perfectly on
(?m)Order your copy
The minute I do anything to the regex to make it match the line before or the line after, it doesn't match anything.
Are you able to test any multiline regex (ideally from a pdf source) either using the remove header or remove footer options, and have the regex builder highlight two or more lines?
If it helps, I'm running calibre 0.6.49 now, but I couldn't get it working in 0.6.45 either.