Strange Joint Behaviour

So I'm trying to make a slime-like 2d object and I used this video as a starting point:

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I made the first object in the video but added a bunch of nodes so i have an object like this: https://gyazo.com/bb091b5e009bcb0ded598fa058a0af6f.
It all worked fine so I made a script to shoot the object from one place to the next and made it stick to walls:https://gyazo.com/fa4b36ea35e882ac1aa3b74a8b2dfd35.
The next step was to make the walls move so i tried setting the parent of the object as the wall it was sticking to and noticed that the object doesn't becomes a circle after leaving the wall and being re-parented: https://gyazo.com/8c24b876b6ca836fec5b2203d6dbc303 as it did before: https://gyazo.com/0e7264dff7ca6484a9d5aa5da3ca91f6. Also if the wall is moving something even stranger happens:https://gyazo.com/60e2795916c73f0658d8268ec480e3b2.
Any idea why this is happening?

 

Are the objects you're colliding with kinematic bodies? That could in part be the reason for the deflating blob. Kinematic bodies don't have density like a rigid body rotating with a joint. Also, if you're modifying the density of the circles in the blob, I believe that can affect the 'softness'.