I found a bug in the two-phase.h file when using FILTERED. If FILTERED is used, then the initial capillary time constraint (in tension.h) is far more strict. The reason is that the rho is computed as rhov = cm*rho(sf) in the properties event. However, sf is not computed until the later tracer_advection event. This means that the variable ‘rhom’ is then incorrectly determined in tension.h stability calculation.
Attached is a simple example.