Viewport stuttering and unable to select objects after opening VFB or after a render finishes

[Alex_M]

I've noticed that with Vray Next update 2 Max occasionally starts stuttering in the viewports and I'm unable to select objects. It seems that it happens when I open the VFB or after a render finishes and I close VFB. The same problem occurs on 2 different PCs (same hardware and software). Anyone else noticed this?

[Alex_M]

Ok, an update on the problem. After a few days of tests, now I'm 100% positive that it happens after stopping a render in VFB. This issue causes me to restart Max at least 3-4 times a day.

[tanya_to]

Hello,
I haven't managed to reproduce it here so any additional information would be helpful. Does this happen with any scene or just with specific one? Is it reproducible with both Max 2020 and Max 2018?

[Alex_M]

Yes, this happen with every scene in Max 2020.1. I haven't tried with Max 2018. I will and then I'll report back my findings.

[Alex_M]

Actually, change of plans. I'm not going to be testing this with Max 2018, because this version of Max has horribly laggy user interface so no point in me going back to it. So anyways, is it just my two workstations? Nobody else experiences this problem?

To add more information that might help with reproducing this, I forgot to mention that the problem only occurs sometimes. So I could go a whole day or two without it occuring and sometimes it happens after the first few renders for the day.

[tanya_to]

Hello! It would be useful if you can record a video and share your log file. Are there any other plugins involved when the issue occurs?

[Alex_M]

Ok, I'll try to record a video if I have some free time. No plugins are involved apart from Vray.

[Alex_M]

So it happened again. I recorded a video this time: https://we.tl/t-bOx0yMQAmw

[^Lele^]

Could those be the two max sessions conflicting?
Viewports have really little to do with V-Ray (comparatively) and a lot to do with Max.

Does it happen as well with other Max video drivers (i.e. old Dx)?
Also, does it happen on a single screen? I have nVidia cards and they had issues with my 5k, dual DP cable monitor (so three DP cables attached to the single card) across three different generations of chip, and countless drivers.
Issues including monitors not waking up from standby, occasionally standby triggers a 100% gpu usage, and the system won't come back, and so on.
If i turn that monitor off, the system behaves normally.

[Alex_M]

Thanks for the input, ^Lele^ I never have two instances of Max running when this happens. And as I mentioned, it only happens after I render something with Vray so it it's definitely Vray that triggers this. Why though I have no idea and this is the first time I've encountered such a strange problem in all my years using Vray which is over a decade now.

I've not tested changing Max to use the legacy Dx display driver, but I will try and report back my findings.
Regarding the monitors and cables, I'm not sure how they could have anything to do with this. Unfortunately I can't test with single monitor, because it's crucial for my workflow and I can't use just one.

[^Lele^]

Thanks for the input, ^Lele^ I never have two instances of Max running when this happens. And as I mentioned, it only happens after I render something with Vray so it it's definitely Vray that triggers this. Why though I have no idea and this is the first time I've encountered such a strange problem in all my years using Vray which is over a decade now.

That's my gripe: V-Ray could just be asking Max to do something, and Max may be doing it wrong, for whatever reason. (We don't know if this would happen to you with other renderers, under similar conditions, f.e., as of now. I only get UI misbehavior like you talk about in 2019 and 2020 with Arnold, go figure.)
So the driver corrupts for the session, and there is nothing to do but start a fresh max/scene (which may reset the drivers anyway.).

I've not tested changing Max to use the legacy Dx display driver, but I will try and report back my findings.
Regarding the monitors and cables, I'm not sure how they could have anything to do with this. Unfortunately I can't test with single monitor, because it's crucial for my workflow and I can't use just one.

I'm not suggesting you should be working with a single monitor, mind you.
I'm just asking you to reduce the number of variables in play, and i know for a fact nVidia drivers are iffy with many DP cables attached.
As said above, i get the UI locking/flashing behavior only with Arnold, under 2019 and 2020. And also only with two monitors active, and 3 DP cables plugged in.

[Alex_M]

I switched to the legacy D3D viewport display driver for a while and Max started crashing every so often.

[^Lele^]

I would keep investigating the video part of your rig, then: the chance we may have two separate bugs dealing with two different video drivers are slim indeed.
You could have, and i hope it's not the case, some kind of fault developing.
Install maybe a demo of a 3d-heavy application or game, and run a few benchmarks to see if you're not running into overheating, or analogous issue.
Likewise, try and do some -heavy- render with Arnold, taxing the CPU and RAM enough to produce heat, and see if it starts to flicker as well.

I am leaning on overheating, as a combination of workloads, personally.

[Alex_M]

I'm not rendering with the GPU and the GPU is also not used for anything other than the viewport when this happens. Moreover, the fans are not ramping up and they would have if the GPU was overheating. I might try different display drivers.

[Alex_M]

I'm still getting this problem on brand new Windows install, different GPU drivers and with the latest official version of Vray. Anyone else? It's extremely frustrating to restart Max after every few renders/IPRs. I find myself restarting it about 20 times a day.