I would suggest passing the various parameters as separate query parameters, rather than as a single body block. I have not used the body text in Sense, so can't confirm whether it should work or not. I have had success passing things individually.
Suggest trying with the minimum number of parameters to get a result back, rather than going for all of them at once. I guess username and password are required, without other parameters you may still get a response?
I see in PostMan things are in the URL Encoded section, you may need to encode some of the values prior to plumbing into Sense.
Finding other REST examples on Qlik Community may help.