Grading scheme of AMCnumericChoice is off (Bug #393)

I am using the questions below (either interval or numeric) in a 16-paper random-order test for my students.
I would expect to see 0 or 5 points for the interval questions, and 0, 3, or 5 points for the numerical, in accordance with their answers.

What I get after scoring is 0, 2, and 5 for interval, and 0, 2, 3, 5 and 7 (!!) points for the numeric ... any ideas what is wrong here?

\element{keplerSkill}{
    \begin{question}{cometApohelInterval}\scoring{e=0,v=0,b=5,m=0}
    \FPeval\FOne{ trunc(1.0 + trunc(random * 3,0),0) }
    \FPeval\FTwo{ trunc(5.0 + 2*trunc(random * 2,0),0) }
    \FPeval\RMin{ (trunc(2 + random * 4,1)) }
    \FPeval\RMax{ ((FOne + FTwo) / (FTwo - FOne) * RMin) }
    \calcQuestion{} A comet with a perihelion (closest distance to the sun) of \RMin ~AU (astronomical units) has an eccentricity $\epsilon$ of $\frac{\FOne}{\FTwo}$. What is its aphelion (in AU)? Select the right interval.~(5 points)
    \begin{multicols}{4}
    \begin{choices}[o]
        \AMCIntervals{\RMax}{2}{25}{2}
    \end{choices}
    \end{multicols}
    \end{question}
}

\element{keplerSkill}{
    \begin{questionmultx}{cometApohelNumChoice}
    \FPeval\FOne{ trunc(1 + trunc(random * 3,0),0) }
    \FPeval\FTwo{ trunc(5 + 2*trunc(random * 2,0),0) }
    \FPeval\RMin{ trunc(2 + random * 4,1) }
    \FPeval\RMax{ ((FOne + FTwo) / (FTwo - FOne) * RMin) }
    \calcQuestion{} A comet with a perihelion (closest distance to the sun) of \RMin~AU (astronomical units) has an excentricity $\epsilon$ of $\frac\FOne\FTwo$. What is its apohelion (in AU)? Calculate the value to one decimal.~(5 points)

    \AMCnumericChoices{\RMax}{digits=3,decimals=1,sign=true,
        borderwidth=0pt,backgroundcol=white, exact=2, approx=5, 
        scoreexact=5, scoreapprox=3}
    \end{questionmultx}
}