I’ve found a bug :
If i use a bitmap (hdri mostly) in Reflexion override and not in the environment (lights), i get some strange rectangular errors in the render : longer to get less noisy and eventually turns black.
As soon as i put the same hdri in the light environment, instead of black color, it works.
Quick solution is to put the same hdri, but via one CoronaColorCorrection with expo to -20, so it is black for lights, but normal for reflexions…
I could not replicate this, maybe it was scene dependant or so.
As i had the known “veeeeery slowww & lags” while IR, i’ve changed several things, bios, drivers and Corona 12.1 hf 1…
If it comes back, i’ll save the scene and some screenshots