Piece ends abruptly after rendering to WAV

When I render my piece of music, it literally ends on the last millisecond of the last bar, as if someone had run out of tape. My workaround is to add a couple more bars in Sibelius before I export the piece to MIDI, but this then makes extra work for me as well as making the score look untidy at the end as those bars don't really do anything except stop the ending being so literal and abrupt. Am I doing something wrong? I have "render entire project" ticked (checked). The playback is fine, it only happens when rendering. Thanks for any help.

You could drag a time selection that spans as wide as you think you need the render to be and then not use "render entire project" but rather "render time selection". Or just insert an empty item at the end of the project.

'Insert empty item' at the end of the song is the quickest way.