Popup Expression Does Not Publish to Portal

[MGAL]

I wrote a custom arcade expression for a popup in Pro (3.3.4) that is supposed to take a measured value & convert it into a station measurement (i.e. 240786.89 becomes 240786+89). When I publish the feature class, the expression doesn't carry over to portal. 

function engm_readable (measure) {
  if(!IsEmpty(measure)){
    var int_measure = Round(measure,0)
    IIF(int_measure > measure, int_measure -= 1, int_measure)
    var float_measure = Round((measure - int_measure),2)*100
    return Concatenate([Text(int_measure), Text(float_measure)], "+")
  }
  else { return Null }
}

engm_readable($feature.engm)

I can copy this same expression up to a web map, and it works just fine. Why is this not publishing from Pro? I'd rather manage my arcade expressions in Pro.