I just upgraded to Unity 6. Before everything worked fine, now the effect its self somewhat works, but its essentially the same as if I had no shadows in my scene, meaning there are no god rays or anything, which I use this for. My main light is just a regular directional light.

I saw that it said that were problems with additional lights and turning on "Transparent Receive Shadows" would help. But for me it seams the problem also exists for the main directional light. Also turning on "Transparent Receive Shadows" solves the issue. Though this just seams like a temporary fix and not good solution.

As a side node, I have turned off "Compatibility Mode"

I might investigate this further.