Dear customer,Regarding Flickering.
This is known Vray artefact. This is caused due to noise in GI. You need better Global Illumination settings, so they do not fluctuate during the animation. There are few ways to achieve that. Simplest is to use BruteForce for both pirmary and secondary GI bounces. Here is quick crop of Your render using BruteForce/BruteForce:
There are other settings involving LightCache and IrradianceMap, that can be quicker to render but needs more time and tests to set it up. Please refer this in ChaosGroup forums.Regarding disappearing Forest Items:
Your scene has been created or edited with a non-legitimate Forest license. Disappearing items are part of our protection system.
Please check if you have imported the Forest object from an external source (downloaded from Internet, third-party freelancer, etc.).
We cannot check the origin of your scene, but for sure the object included on it was created using a non-legitimate license.
Please delete all the Forest objects from it and recreate them from scratch. Trying to move the settings from this contaminated scene can cause instability and possible future issues.
If You continue to have disappearing objects, when creating ForestPack items from scratch, that means illegitimate license is on Your system and You need to remove it.
Please write us firstname.lastname@example.org
and we will continue the conversation.
P.S. General tip: always work to true scale and near 0,0,0 coordinates. Now Your current scene is far from origin and very very large. Working in scale is quicker and not doing so can cause other issues down the line as well.