fsnotifywait breaks xsystemd-idle-timeout – how to solve?

I am using fsnotifywait on a device that is controlled by a systemd automount unit.
Setting xsystem-idle-timeout=1m for /mountpointx triggers an unmount event after timeout, if fsnotifywait is not running.
But after starting fsnotifywait –monitor –filesystem /mountpointx no unmount event occurs any more.
How to enable idle-timeout while fsnotifywait is running.

The system is debian 13 trixie, kernel 6.12, Systemd 257.
ExtraOptions=strictexpire has no effect.