atmTurb.HeatFluxTemp. with buo.Bouss.PimpleFoam raises unallocated autoPtr

Summary

buoyantBoussinesqPimpleFOAM crashes when using atmTurbulentHeatFluxTemperature BC.

Steps to reproduce

Run a atmForestStability tutorial with SIMPLE->PIMPLE replacement.

Example case

What is the current bug behaviour?

On the 2nd time loop, solver crashes on executing TEqn.H.
A 1st time step looks fine.

What is the expected correct behavior?

Relevant logs and/or images

--> FOAM FATAL ERROR: (openfoam-2112)
unallocated autoPtr of type N4Foam9Function1IdEE

    From T* Foam::autoPtr<T>::operator->() [with T = Foam::Function1<double>]
    in file /home/xxxxx/OpenFOAM/OpenFOAM-v2112/src/OpenFOAM/lnInclude/autoPtrI.H at line 178.

FOAM aborting

#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::error::simpleExit(int, bool) at ??:?
#2  Foam::atmTurbulentHeatFluxTemperatureFvPatchScalarField::updateCoeffs() at ??:?
#3  Foam::fvMatrix<double>::fvMatrix(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::dimensionSet const&) at ??:?
#4  Foam::tmp<Foam::fvMatrix<double> > Foam::fv::optionList::source<double>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::word const&, Foam::dimensionSet const&) at ??:?
#5  ? at ??:?
#6  __libc_start_main in /lib64/libc.so.6
#7  ? at ??:?
Aborted (core dump)

Environment information

OpenFOAM version : v2112
Operating system : Red Hat Enterprise Linux Server release 7.4 (Maipo)
Hardware info : Xeon cluster
Compiler : GCC10.3.0 (built in ThirdParty)