Help trying to create a Translohr/Bombardier GLT system

I’ve been experimenting with creating a system similar to what’s been employed in the French city of Nancy, which uses a type of trolleybus/tram system known as the Bombardier GLT. This system is unique in how it can function like a tram in how it has a guiding rail in some parts, a trolleybus in how the vehicles can operate off of the guiding rail but still be connected to the overhead wires, and as a regular bus in how it doesn’t need rails or overhead wires to function.

But there’s an issue.

Every time I try to enter the vehicleseat, it jumps off of the guiding rail, and every time it goes around tight turns, the guiding wheels mount the road surface and come off track.

How could I fix this while maintaining the versatility of the system? This means that I can’t fix the vehicles to the guiding rail, as the driver should be free to decide to turn off the guiding system, but at the same time, I want my guiding rail to be fully functional.

Note that in the middle of every axle is a guiding trolley, and there are 4 axles on each bi-articulated bus.