Typically, your model not satisfying the Blanchard-Kahn conditions for most parameter values indicates a timing problem, i.e. a mistake in the model setup. The less likely second possibility is that your prior region was chosen poorly and only allows for a narrow range of parameters that satisfy the BK conditions.
Note that if you model features a unit root, you can get a behavior like this during identification analysis if you forget to specify the diffuse_filter-option.