When text crosses a barline, it is useful to make ["erase"] a space in the barline for the text to cross. Up to Sib 7 I used whitespace tif's for this but with Sib 7 I changed my method to using the typgraphic controls in the inspector.
I now select the text / select Text Frame from the Inspector, give the frame a little extra height and select the [vertical] alignment. Then I select erase background.
This all looks good on the screen but when I go to print preview I see the text is obscured the "erasing" background. To fix this I find manually selecting the right toggle of the text frame and pulling it right or adding a +1 space to the Width of the text frame in the inspector corrects the situation.
This bug is easily reproduced and after I started to see this I ran a print preview every time I created this effect which - along with reporting problems like this - costs me time.
There are other aspects to this problem but this is the basic one and I leave it to the developers to get their heads around it.