Hello crop team rep!
Just like the post above me I planted all of the crops at the same time. All had unrestricted access to sunlight as they're located on the third floor of our homebase which has plenty of windows to the side and skylighting (glass blocks) in the ceiling so the sun can shine through. One thing I have noticed is that if I log out near the crops when I log back in the problem happens. However, if I log out away from the crops, like down on the first or basement floors of our homebase, or away from the base, the crops grow just fine and on time.
Also, as an additional question, is the 50% return supposed to work on all or just some plants? I run 100 plants at a time and have noticed that harvesting certain crops (like corn) will correctly apply the 50% return and I walk away with 50 seeds. But with other crops like potatoes and pumpkins, it will not correctly apply the 50% return and I walk away with 30 seeds out of 100 plants.