When mounting a fuse-type mount, the actual fuse program is ran as a service (daemon) in the system.

When you access the mount point, doing so under strace (example: strace npm ci) won't trace the fuse service.

To debug the actual fuse, you should mount it with the -o debug flag.

And if you really want to strace it, find the service PID using ps and attach it to strace using strace -p.