Issue with inferring initial conditions for variables used in der()

[greenwoodms06]

I am testing porting simple Modelica models over to Modia to test its capabilities, syntax, etc. I have an issue with inferred initial conditions. The code below is a lumped heat capacitor (i.e., volume).

When using the UnitVolume component below in a simple example, it provides the following error
LoadError: Missing start/init value unitVolume.U

However, U's starting value comes from the value specified with the provided parameters and the start value set to T.

My simple test works if I modify the code and remove T = Var(init=(180+273.15)u"K") and instead set U=Var(start=6000.0u"J"). However this is not an appropriate solution of course. Variations of start and init didn't seem to fix the issue either.

Questions:

1. Is this ability to derive initial conditions from other variables a limitation of Modia at this time? If not, any suggestions would be appreciated.
2. Removing U and m and replacing der(U) with der(d*V*cp*(T-T_reference)) also fails. Does Modia not support equations within the der() operator at this time?

Model

UnitVolume = Model(
    nParallel=1,
    V=1.0u"m^3",
    d=1000.0u"kg/m^3",
    cp=1.0u"J/(kg*K)",
    Q_gen=0.0u"W",
    T_reference  = 273.15u"K",
    T = Var(init=(180+273.15)u"K"),
    port = HeatPort,
    equations = :[
        m = d*V
        U = m*cp*(T-T_reference)
        Qb_flow = port.Q_flow / nParallel + Q_gen
        der(U) = Qb_flow
        port.T = T
    ]
)

[HildingElmqvist]

Your observations are correct. Both these features are not supported yet.

[greenwoodms06]

Well alrighty then. I'll stop trying to force it to work! haha.

Thank you for your response.