I found this but it is not intuitive at all and it's 6 years old. So, I wonder if the answer by gaborous is correct as I am using Lyx 2.2.2 and simple enter does not do the job for me:
@landroni in latest versions of Lyx it seems the shortcut is no longer necessary, a simple enter is enough to do a linebreak. – gaborous May 31 '16 at 20:54
Is there an easier way to do this? Is the answer by gaborous correct in any circumstance?
makecellpackage, which allows for line breaks in standardr, c, lcolumns. See my answer to (https://tex.stackexchange.com/questions/2441/how-to-add-a-forced-line-break-inside-a-table-cell) – Bernard May 04 '17 at 15:30