Point lights are killing my directional light's cast shadows.

Created a directional light. Tested - OK. Created a pointlight. Tested - Now the directional light shadows are flickering and vanish completely. I'm using Unity Version 2017.1.0f3 Here's a link to a short clip I created to demonstrate the issue - https://youtu.be/lyxu2r-bJ_M

Any help would be appreciated. if you need any additional information feel free to ask. :)

EDIT: Just a note, that the shadows produced by the directional light reliably vanish when any of my point lights are in the camera view.

I've also tried adjusting the pixel light count in the quality settings. Setting the directional light to realtime and adjusting the intensity, strength, bias, normal bias and near plane.

EDIT 2: After some more investigating I was able to pinpoint the source of the problem. I have several particle systems in my scene that I plucked from Unity's Particle System asset. It turns out it was the a particle system meant to cause torch lights to pulse that was causing the problem. I recreated the same particle system from scratch and was able to replicate the issue. I will be removing the pulsing light particle systems and working on a better work around via scripting.