My metahuman character floating while seated when changing between animations

Hello everyone, sorry if this question is not so organized since it’s my first time posting here. I have been stuck for more than a month on this issue and I never saw anyone talking about it, so I probably have something set up wrongly.

I have a lecture room with 10 Metahumans. I wanted to have all the Metahumans seated and playing some idle animations (they need to look realistic) while looking at my player. I started by getting seated animations from Mixamo and using a Random Sequence Player node to switch between them, where I found my problem. The character was moving horizontally between animations — basically the character floats in space and moves when blending into the next animation.

My next approach was using a pose and then adding the motion as additive, and I still got the same moving issue. I tried fixing this by adding an offset to make both animations start at the same place (I tried offsetting in Blender and in the Sequencer, then baking into an animation clip again), and it still doesn’t look realistic and the body movements look very fake.

I want to know what the best approach for this is. How can I fix this movement issue? Is there anything I am missing?

I also tested many times with Force Root Lock enabled and also by removing the root translation in the Retargeter asset, but still got the same output. Any help would be greatly appreciated since it is really urgent for me to get this working.