I start a new document. I insert a table. I hover over the column border, press the left mouse button and I can change the width of the column. I hover over the row border, press the left mouse button and nothing happens (or I simply select a range of cells). The mouse pointer correctly changes to the double-headed arrow for row height sizing but the action doesn't occur. I can only size rows through the menu.
On Windows 10 Pro 64-bit with Version: 5.0.2.2 (x64) Build ID: 37b43f919e4de5eeaca9b9755ed688758a8251fe Locale: en-US (en_US) All seems to work correctly. Please verify that while inside the table, the table object has focus. It may be easier to see this if you go ahead and enable the Vertical Ruler check box from Tools -> Options -> LibreOffice Writer -> View -- when the table actually has focus the vertical ruler will resize to the active table. Also, note that the top edge of the table is its positional anchor and that the top row can not be dragged from its top edge downward to shrink that row. Rather from its bottom edge and drag upward toward its anchor. To adjust separation from paragraph above, or from the page margin--while focused in the table object--use the Table Properties dialog to adjust Spacing Above or Below the table. The Left and Right spacing in the dialog effectively reposition the table between the page margins.
Fixed for 5.0.2. Please upgrade. *** This bug has been marked as a duplicate of bug 92145 ***