I formatted a paragraph with a single border only before the paragraph. The padding is set to 0,20 cm. If the check box „Synch“ isenabled, the padding for the not set borders (left, right and bottom) are also set to 0,20 cm and (and this is imho the bug) the paragraph will padded 0,20 cm even there is no border.
Padding and borders are independent properties. Therefore it is correct, that a padding is applied without having a border. In the upcoming version 5.4. this will be reflected in the UI and all padding fields will be enabled, independent of the borders. In the meantime, with older versions, you should first enable temporarily all borders, set the paddings you need, and last enable only the border you want. I suggest to resolve to "worksforme".
As long as I haven´t an element, I expect the padding for the paragraph not at this position. I do excpet it only if I have a line there. The workaround you suggest is not a straight logical solution.
"If the check box „Synch“ isenabled" <- this is all perfectly logical. Closing.