FIRHalfbandInterpolator 'transition width' specification causing an error

When using the FIRHalfbandInterpolator system object with 'Specification' set to 'Filter order and stopband attenuation', I get this error calling "step":

 Error using coder.internal.errorIf (line 8)
 The transition width must be less than 400.0 (half the output sample rate).

 Error in dsp.FIRHalfbandInterpolator/validatePropertiesImpl (line 232)
            coder.internal.errorIf(TW >= outputFs/2, ...

When checking line 232 in the source code above, I noticed that

obj.TransitionWidth

Is called and an exception is thrown if the transition width exceeds the cutoff frequency. This parameter is not explicitly set when using the above Specification identifier, yet the default value is not appropriately replaced. Unless I am missing something, I have to manually set this value and "set" runs fine.