I have a spreadsheet with all cells formatted with vertical alignment to the bottom of the cell, and all rows formatted with optimum row height (I keep clearing the "default height" check box, but it keeps getting turned on again). Most rows contain from 1 to 5 text lines in the tallest cells, but a few contain over 20.  After sorting the entire file, which moves some rows of course, some rows contain too many blank lines at the top, as if their cells had inherited the formats of cells previously in that row number.  Restoring the old values can be done by double clicking the too-tall rows' lower boundary in the far left column.

In addition, the above mentioned double click does not always cut the top margin of blank space down to the normal half-line height; some of them keep 4 or even 5 line heights at the top (and there are no line feeds at the top of the cell), but can be manually cut down by dragging the lower boundary with the mouse.  But it always reverts to too much space at the top when the cells are updated or the rows moved via sorting.