It looks like you have a boundary condition at that level that is removing shear from the structure. Right?

Thank you JoshPlum for your logic reply. I will try to find this boundary condition. I have four basements surrounded by RC walls.Should I look for lateral support at that level?

Yes.... Even it's it just lateral soil springs this can happen.

Think about a 12 ft long cantilevered column that rises 10 feet in the air. With 1 kip of lateral load applied at each foot. Then it's supported a 0 ft and -2 ft by lateral support. You'll get a force couple between the shears at the 0 ft and
the -2ft locations to take the moment. But, the total lateral reaction should add up to 10 kips

Thanks again JoshPlum, I appreciate your prompt reply and spending your time clarifying the case with a very easy to understand example. I will find the lateral constraints that are causing this issue in my model and will keep you updated. Best Regards