The Big Weird Bug. Now with VrayLight.

[Escape-nc]

Hello mates!

This is how we do it.

All you need is one any Vray Next (I've tested 4.02.05 and 4.10.01) and 3DsMax 2018 or 2019.

Now open your max, set up vray as render engine, add plane to the scene and now we are gonna do some serious seriousness! Add VrayLight to the scene, make it DISK or SPHERE type and move it to any position where X and Y are EXACTLY the same. Z can be anything you like. For example: 40:40:25.

Now make your light targeted and move the target EXACTLY at 0:0:0 by XYZ position (Z can be anything though).

That's it! Press F9. Do you see light? Me not. These bug happen only with disk and sphere types of light and only when the target is at 0:0:0 and X-Y of light's position are exactly the same and have positive values. Change anything of that and it's gonna work properly.

Or... you can download my scene and try it by yourself. It's for 2018 and 2019 versions of max. Just open and press F9:
https://dropmefiles.com/PeJuG

Here is the pics:
https://imgur.com/a/Rn68the

Hope you know what it is and how to fix it. Thanks!

[^Lele^]

reproed.
What an odd one!

As a workaround, it's enough to add the smallest amount possible to either X or Y (the least visible spinner digit, hoever the spinners' precision is set. f.e. 35.0 -> 35.001 ).

[Escape-nc]

Yeah, I've mentioned that. Any change to amounts and it's gonna work properly. And by little chance it can be dangerous when you render animations or you somehow "linked" to same integer numbers or so... Well, right now it's simply annoying.

[^Lele^]

Indeed, i should have written "temporary" workaround, eheh.
Of course it's annoying, and besides checking for the value of light positions at each frame, to then nudge them (adding keys to animations, ugh.), there is little value in knowing about the workaround.