What's the maximum range on Runaan's Hurricane?

In these images I play as Senna with over 1000 stacks and try attacking a group of target dummies with Runaan’s equipped. At some point the bolts no longer fire, even though all the targets are well within my auto range and close to each other. In the first picture no bolts fire, and in the second picture only one bolt fires. In the third picture I move slightly closer and both bolts fire. Is anywhere documented the maximum range of Runaan’s or is there another reason for this behavior?

I don’t believe it to be related to a prior bug where Runaan’s would not fire when bolts are in midair. With Tristana, one can test this bug with Hail of blades and there can be four Runaan’s bolts in midair for a brief moment. Interestingly enough I can’t get more than 2 bolts in midair on Senna.