When using GNOME on Wayland I can't move the pointer with the touchpad
if I initially start touching it near a corner. Even if I drag my finger
across the middle from the corner, the pointer doesn't move, and no
events are shown in libinput debug-events. If I do the opposite, ie
start the motion near the middle of the touchpad, it continues to track
my finger correctly if I move it into the corners.

I first noticed this problem shortly after libinput 1.8.2 entered Debian unstable and reported it there: <https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=876198>. I'm now using 1.9.3 and still experiencing the problem. GNOME on X11 doesn't have this bug, so I think it must be libinput's fault. BTW, neither libinput's nor any core wayland packages in Debian seem to match the version numbers available in the bug tracker menu here, which only go up to 1.5.0 (libwayland packages are showing as version 1.14.0, wayland-protocols as 1.11).

The machine is a Lenovo Thinkpad Carbon X1 4th Generation. From
libinput list-devices:

Device:           SynPS/2 Synaptics TouchPad
Kernel:           /dev/input/event1
Group:            8
Seat:             seat0, default
Size:             100x57mm
Capabilities:     pointer gesture
Tap-to-click:     disabled
Tap-and-drag:     enabled
Tap drag lock:    disabled
Left-handed:      disabled
Nat.scrolling:    disabled
Middle emulation: disabled
Calibration:      n/a
Scroll methods:   *two-finger edge 
Click methods:    *button-areas clickfinger 
Disable-w-typing: enabled
Accel profiles:   none
Rotation:         n/a