Can we think about the male sterility as one of the reason. Because male sterility may not allow the formation of pods or seeds. I also agree with the opinion of "Dalia Youssef", as climate change say for example drastic increase or decrease in temperature may also cause male sterility hence no seed or pod formation.
Canola is vulnerable to a number of seed and seedling diseases. ... Seed-borne fungi rarely cause canola emergence problems if seed is properly treated.