In 2018 my employer was in California but I lived in Tennessee. Should I be taxed on my income on my California return?

California gov website says: Nonresidents of California - Taxed only on income from California sources. On CA540NR line 1, there are amounts in boxes A C and D but box E says zero, so it's showing a full refund of all of my taxes. Is this correct? It sounds like I should be taxed.