Aside: AFAICT, this is not a duplicate of any other bug. When setting up the parameters for a label (specifically Avery 5160, but it is a general problem), the Horizontal Pitch parameter does not establish the horizontal pitch (of multiple labels across the page). Instead, the Width parameter sets the horizontal pitch. This is not as it should be and causes problems. I did try to set the Width to the required horizontal pitch (2.75") which did establish the horizontal pitch (my workaround), and thought that maybe the two parameters were reversed, so I tried to set the Horizontal Pitch to 2.5" (which is the correct width of the labels), but that apparently is not the case. Well, I'm not 100% sure because there is apparently code that prevents the Horizontal Pitch to be set to a value less than the Width (which makes sense / is appropriate), but I could not test the hypotheses that the two parameters were reversed.
Oh, one thing I did that helped me measure the horizontal pitch while experimenting was to put a vertical bar "|" at the very top left corner of the labels. (I did have to backspace a little to get to that (far left) position -- I don't know why, but I'm not complaining about that.)
Ok, I found another bug that appears to be a duplicate of this and was apparently fixed in version 3.6.0.4. Sorry for the noise! ` Tested with LO 3.6.0.4, works fine now - thanks a lot! ' *** This bug has been marked as a duplicate of bug 51332 ***