WyuRi

I need 40 basic rectangular blocks printed. I then encountered the same issue I have in the past where if I make more than 10 copies of an object, some as simple as a rectangular block, the slicer just freezes. See my image, I tried making 40 copies of that rectangular cap, cant slice. I halved it to 20 and still can't slice. It finally sliced with 10 copies. What the heck, I dont want to print a 1hr print 4 times. What is going on?? Anyone knows or had this issue?