NaN and Inf result from improper expressions. In Matlab, things like “0/0”, “Inf/Inf”, and “Inf - Inf” evaluate to NaN, and anything mixed with NaN is also NaN.
Something in your steady state block or file is evaluating to Inf or NaN which is blowing up the steady state values. I would suggest using the “resid” command to see which equations are not solving, and try to figure out why your steady state is producing these results. Without seeing your .mod file it is not possible to say more.