Whenever I use the particle system to emit from volume, it just ends up emitting from the faces. Is this a bug? I've just started using Blender particle system and rigid body stuff. I've tried to emit particles from the volume of the mesh but they just sit on the surface of the mesh no matter what I try to do.

I want all the particles to be inside the mesh from the beginning and not on the surface. Is this possible?

I was following this tutorial - https://www.youtube.com/watch?v=1gM8yEMFMjg

The particle system with random distribution

Here is the system with jittered distribution

Emit from Verts and faces yield similar results with some particles escaping the mesh in the first frame itself.

Here is the blend file if I wasn't able to explain it properly: https://drive.google.com/file/d/1eRWzE-IprJ0dP3l_zxkEso5sTgC0Vbq7/view?usp=sharing

Any help would be appreciated!
The end frame for your simulation is the same as your start frame. That means that your particle simulation will run for one frame (in which it will emit the particles), and then stop playing. 

Simply change it from 1 to the desired number of frames you want your simulation to run for (if you don't know what this is, then just set this to the number of total frames your project is set to render, which I can see is 250). 



Simply put, set the Frame End to 250 in the Particle System Properties tab.