Logbook triggers for recording takeoffs/landings

We have been having some user reports in our aircraft of occasions where,
although the flight length is recorded in the logbook, there are no takeoffs
or landings being recorded. What are the triggers for the sim to record the
takeoff and/or landing? The aircraft in question contains a significant level
of custom WASM-based functionality. I’m sure we’re affecting something that in
turn is preventing the takeoff and landing from being recorded, but we have no
idea what it might be.