It sometimes happens that a table row is tallest than the page's height. When it occurs, the overflowed data is present on the next page but without its styles (borders, colors, etc.).
The bug can be easily reproduced. I adapted the table demo sample provided with the source tarball so as to reveal the problem (see attached JRXML file).
Beware that this use case also reveals another known bug : "[#5010] Band Element splitType = "Prevent" introduces blank pages".
I'm investigating on it but couldn't find any workaround yet.
PS: I suspect this is the same bug as bug "[#5580] Table row color breaks when exceeds page limit" which is probably erroneously assigned to iReport project.