Try to use Collision Resizer addon.

Possible conflicting addons. If this continues to happen and you used Collision Resizer addon, its conflicting addons. Probably you need to get rid of the conflicting addons to stop this, and it will not happen.

Originally posted by YounYokel:

Try to use Collision Resizer addon.

Sadly, it didn't help

Originally posted by Peanut:

Possible conflicting addons. If this continues to happen and you used Collision Resizer addon, its conflicting addons. Probably you need to get rid of the conflicting addons to stop this, and it will not happen.

I disabled all mods, except this one. Same render problem.

No addon conflicts, absolutely any bone manipulation on props(not ragdolls) messes up model culling system on prop.
Seems like there are no fixes for this problem.

Originally posted by Merydian:

No addon conflicts, absolutely any bone manipulation on props(not ragdolls) messes up model culling system on prop.
Seems like there are no fixes for this problem.

so it's called culling system. I didn't know that.

except there is very complex fix via ingame means.

1. Spawn a prop
2. manipulate prop's bone, or use SMH on it.
3. right click on prop "make animatable"
4. move it a bit to refresh render
5. pick the lamp tool that has directional lighting. set to high radius and high distance via manual number override, because default slider limits won't let you set it to 10,000 for example.
6. put two lamps with these parameters from two opposite sides that aim at prop
7. It's visible again under any angle.

This is what I discovered later.
https://youtu.be/pi9wPZqetaw

Yet, this solution doesn't well with 3d skyboxes.
Turns out if you have 3d skybox landscape, the lighted prop whose culling was tampered with bone tool or SMH - it flickers like mad.
So you have to turn off 3D skybox via command. I forgot what exact command was to disable 3d skybox, but it's in gmod command list.

I also heard that even Source Film Maker movie makers suffer same problem with huge props.
While looking for a solution, I just found this old post that was about similar problem.
https://steamcommunity.com/app/1840/discussions/0/684839199047712632/

I guess my trick is better than re-edit each prop for different. Although, it depends on what each film makers aims to do.

This is cool that you discovered it, any solution is good but still not a complete fix. We can only hope to devs.

Originally posted by Merydian:

This is cool that you discovered it, any solution is good but still not a complete fix. We can only hope to devs.

We need a careful update I want to highlight. Because last major update was a tough thing to endure.