Then that is probably why it does not recognise that you are docked.
This post (among others) summarises the needed configuration: UPERFECT X Mini lapdock works with Librem 5 - #94 by Altor
.. in order to associate mouse events from a touchscreen back to the display. (The point is that mouse events from a touchscreen come in on one device but that device bears no relationship with the corresponding display device, particularly if using HDMI output to a touchscreen but even when using USB-C video altmode to output to a touchscreen.)
It wasn’t obvious to me - from the lsusb output - which USB device among the several that appear when you connect a lapdock is the correct one to use but I guess you will work it out for your lapdock.