So three things.
First you are looking at the image in 8 bit – always remember this. The LUT that’s changing the image so you can see it may be faulty or just not expecting the extreme things you are doing to the image.
Second depending on the filters used, you may be using one that is not capable of 32bits and then all your good work at 32 is knocked down to 8 somewhere in the render pipeline and at that point the conversion might fall down and start clipping.
Last, if you are compressing the video so you can see it running, the codec might be doing the clipping for you, or more likely you are trying to send out of AE a 32 bit image into a media holder that is not capable of holding 32 bits, so those subtle colors available in 32bit space get slammed to far ends of the spectrum in the final 8 bit space.
Can you provide any more info on the pipeline?