Ласкаво просимо на GTA5-Mods.com

Hi, so I've been having this issue where I don't have all the cars available to me in the spawner. Now what I mean is that what seems to be random cars are available to me, for example this: https://gyazo.com/d4ab71fd66737deabf14f562c21866cd
Now things to note is that, it's missing even base game cars, but when I look at the VehiclesList.xml, everything is there. Also all saved custom cars, even ones that aren't showing up in the list that I made several months ago, work just fine, but anytime I make a new vehicle that isn't on the list of available cars, it saves the car itself, but the color is always different and none of the settings save.
I've tried everything I can imagine whether it's using a different version of the mod, even using custom variations of the mod that have the same base, making sure the GTAV directory has the appropriate read/write permissions to much, much more.
What I've also noticed is that if I delete the vehiclelist.xml file, I get the same vehicles list when using the spawner. I've been banging my head on this issue for the past week, and if you have any insight on what would cause this kind of issue please add me on Discord: JustCallMeAlec#6453, I'm going insane over this.
I also should note, yes I've tried using the latest GitHub version.

There's a bug I've been trying to fix via editing the source code but still have yet to succeed in.
The bug is when you spawn certain MP DLC vehicles with Menyoo what'll happen is that the game will just kick you back out of the car no matter how many times you attempt to reenter the car. Examples of vehicles that have this bug are the Vagner, the Visione, the Scramjet, the XA-21, and the Deveste Eight . (But there are plenty more)
Vehicles that DON'T have this issue are some like The Sultan RS, the Banshee 900R, The Bullet, Cheetah, the 9F/Cabrio, and many others.
Would you be able to at least point me in the direction of where I need to look to at least make the change myself? At this point I'm just baffled and curious why I can't seem to figure it out.

But does it work in MP?