IPR keeps running in background

[rikU2849]

Since the last 2 Maya releases (post Maya2021) I have been experiencing a very random bug.
When you stop the IPR (either by pressing the Stop button or simply pressing ESC).
He keeps on calculating the render in the background.

So visually in the UI maya looks fine, nothing wrong.
But in the taskmanager , CPU is at 96%. When you press Play in the IPR again, it goes very slow simply because now he's trying to render 2 scenes at the same time.
Needless to say that this is very annoying since the only solution is restarting maya completely.

[LFGFX3D]

I've had that same issue but for me, it happens specifically on GPU render and on scenes with render layers. When I start the render on one layer then stop it and switch to another render layer and try to render, I get a message that parallel render is not supported. GPU usage is at 100%. As you said, the only workaround is to restart maya. Hope the Arnold team fixes this soon.

[Stephen.Blair]

What version of MtoA?
The version of MtoA shipped with Maya will be an old MtoA, a newer one will be available from arnoldrenderer.com/download