LrC 11.0, but it happened in 10.x (I reported it a year or so ago but it was not even acknowledged back then)
Windows 10 Pro x64
When using the Print module, a thin white line often shows at the bottom of the displayed image.
It happens only onscreen (i.e. not in the output JPEG file or print) and depends on the actual display size of the image. If I change the LrC window size or hide some panels, in sometimes disappear. In this case (outputting an aspect ratio of 4x5 portrait), just pressing T to hide toolbar makes the displayed image a bit bigger and the line disappears.
With an output of 3x4 portrait, for instance, it doesn't show with the toolbar either shown or hidden, but if I hide the top panels (F5) it appears (with or without toolbar).
In 5x7 portrait, it appears with or without toolbar.
In 16x10, it appears with the toolbar hidden.
And so on... as mentioned, it's purely based on the actual displayed image size.
It would be nice if at least it weren't ignored again.
Michael Niessen - Photographer, photo-editor, educator
Photo-editing (Ps/Lr/LrC) and photography workshops & one-on-one training (off- and online)