Optimal row height won't stay set

Using LO 5.3.0.3, when using Calc, I use a template with a bunch of the rows formatted to optimal row height plus 0.1". The cells are used for sentences of various lengths and set to wrap automatically. However, when I add a fresh sentence to a cell that requires a new line to wrap, the cell doesn’t automatically grow to accommodate it, so I have to reformat the row to optimal height each time, which is annoying. What am I doing wrong, or is this actually what it’s supposed to do?