Might be your stabilizers...
Try doing more stabilizer work with a lot less weight (around 20-30 pounds) on the lat pulldowns, seated rows, and straight arm pulldowns for higher reps (10-12) to make sure your form is good. You just listed five exercises for your lats (primary) and biceps/shoulder (secondary/indirect/stabilizer)...are these done in that order every time you hit the lats? How much time are you using to warm up? How many reps and sets are you doing? Make sure you stretch between sets if you start to tighten up. Are you arching your back enough during the rows to actually feel the lats working?