Dispensers/Redstone randomly stops working.

Using redstone and dispensers as shown in the screenshots randomly makes the dispensers not dispense anymore.

As seen in screenshot 2 the redstone appears to be active yet several dispensers stop working.

Re-applying the redstone fixes the problem for 1 redstone signal pulse, then the same problem occurs again. checked the dispensers, affected ones have more tnt than the none affected ones.

Tested in several areas/biome's.