VSDC effect not applied during export

I'm addressing you informally because that's the rule in forums in general, not out of disrespect.
First of all, I'm not an expert in video editing as I usually only do simple things, but I manage to handle more complex tasks by reading and watching a lot of tutorials.

Your project seems complex (adding LUTs, movement, or others), so it's difficult to pinpoint what might be wrong.

Could you take a screenshot of the video tab 0391_3 (at least of the first video if it's the only one producing this issue) because that's where, if something should "mess things up," it should be found?
I might be seeing the disappearing effect, but that's hypothetical.

And what is this first video that is placed above all the others?


Finally, it might be the software that's bugging out because, although it's fine for me, it's not amateur or professional software like Premiere, Vegas, or in "free" DaVinci Resolve, for instance.
I hope at least you have a powerful enough machine because the more complex things you do, the more computing power is required.

After several attempts (this is how I proceed, I redo my work a hundred times until I understand or give up), I think I understand what's going wrong on your end. Since you have many overlaid elements, it's difficult to get an idea of what you want to do...
For me, the video with the green screen needs to be placed above the overlay video, but in your case, it seems to be underneath (the background removal effect does not seem to be applied in any case!), but I might be mistaken since the preview on the timeline seems to indicate otherwise.

Now I'm digressing about another of my discoveries... No, that's not it... in my case, the cause comes from stretching the video with the green screen beyond its original duration. In this case, you need to copy and paste the video to extend the effect, which needs to be applied again.

Well, it’s late, so maybe until tomorrow, good night.

Hello comrade Ziggurat, thank you again for your involvement

Here is the zoom on tab 0391_3 with the background removal effect:

I applied the chroma key effect to video 0391_3 (of the colorful character) before cutting it into small pieces (to move the character on the screen), which means that the background removal effect is multiplied across all the videos on this line.

Someone pointed out that the "by TSL model" option might be limited in number because it’s an option in addition to the paid version (although the limitation is not mentioned in VSDC), I need to see if I switch to YUV mode
which bothers me since I have to modify it for each section...

The video in the foreground is a layer of visual effects set to screen mode, for style, and also to avoid copyright issues from using non-free footage in the background haha

I will experiment
I have faith in VSDC

Well, since you are using the paid "Pro" version of VSDC, I'm afraid my help may be very limited, especially since you are doing things that are unknown to me.
I don't have access to the TSL mode (HSL for Hue Saturation Lightness in English), for example, with the free version.

I'm trying to reproduce what your screenshots show with a few small test videos to see what might be wrong. Because it's right from the beginning that it crashes.

If I understand your project correctly, you have a video that lasts the entire length of your project (about 9 min 24). Then you have various videos that have Chroma key videos taken from a single Chroma key video that has been cut. These parts are resized or not to reveal the first video in the background. Is that right?
Why isn't that background video taking precedence over the rest of your project then?
For you:
For me, I would do it like this:

Or is it, as their different names (0391_8, 0391_32, 0391_28, etc.) suggest, that there are several Chroma key videos?
In any case, I don't understand why you have in the object explorer 3 videos at the beginning. Ah, perhaps you copied and pasted the same background video at the start... ;-)

However, if I understand correctly, it crashes at the level of the cut and the application of the Chroma key effect on the little figure.

I applied the Chroma key effect to the video 0391_3 (of the colored guy) before cutting it into small pieces (so I can move the guy on the screen), which means the background removal effect is multiplied across all the videos in that line

.
I think the cause could come from the cut. To make myself understood, although your way of doing it seems practical, it may generate conflicts with the Chroma key. Personally, I would proceed by copying and pasting the Chroma key video if it's unique, modifying the duration if necessary, and placing each "paste" where needed. This method may seem longer to implement, but once the Chroma key effect is applied once, it should replicate with each paste, as you noticed. This remains hypothetical, of course.
On the other hand, I haven't yet explored the case where you have different Chroma key videos...

Finally, there is something that surprises me, but since I'm not a video editing specialist, it may be normal for you:
Especially since there are no videos among all these background removals to rely on.
But this works for me too, so the issue doesn't seem to come from there, at least:

Well, I'm not really helping you as I have many more questions than answers regarding your problem.

Thank you for the feedback ;-)
If I summarize, the issue comes from the TLS mode... strange since the editor advertises this as a professional-level advantage.

World premiere in 3 days, I can't wait ;-)

Wishing you all the best here and elsewhere,
Bye