MultiStageScheme / inner product compilation problem

[Åshild Telle]

I'm trying to couple an ODE and a PDE model for a project, and need to pass an inner product as an argument to the multistage solver. However, even if we mathematically should get a scalar product for the rhs, the scheme won't compile.

The error message reads "ufl.log.UFLException: Nonscalar operator [1.0, 0, 0].". Attached a minimum example.

Would you know @meg ?