Issue driving a shift register
The code and logic analyzer output looks okay. It would not hurt to put a NOP or two before driving the clock high. 

The 74ACT299 is a pretty fast chip (100MHz clock at 5V). I'm guessing you're getting ground bounce between your SR and the driving circuit. This should be suspected especially if you have long wires between the two (make sure the ground wire as well as the signal wires are short and direct). 

You should also have the 74ACT299 power supply bypassed close to the chip with 0.1uF to 1uF ceramic. This is non-optional in general, but especially when you're driving a lot of current into the LEDs. If all the LEDs switch at once you've got ~100mA flying around with nanosecond edges.