Noise has occasionally totally differen results

V-Ray V-Ray for 3ds Max Issues
1

I am working on an ashtray on which I am applying noise for a more realistic refraction.
I am using progressive rendering to see a quick preview.
Sometimes when changing the noise bump settings the result looks different in the first rendering. rendering again afterwards without changing anything results in the true look though.
So Vray 3 is sometimes making an error and calculating the noise bump in a different way - only one time though…the next renderings always turn out the same with the right result.
see attached screens.
buggy rendering:

right rendering:

although I prefer the buggy rendering, I of course would like to have the same result every time I render :roll::stuck_out_tongue:

I am using the latest official stable build btw

ashtray_bug.jpg
ashtray_bug.jpg825×606 128 KB

ashtray_true.jpeg
ashtray_true.jpeg825×606 121 KB

2

Thank you very much for the feedback.
Would it be possible to attach that scene and let us know which steps we must follow in order to reproduce the same issue into our environment?

Thank you very much in advance.