MBP 16" does not recognize external keyboard/mouse after waking up from sleep

Update: I think I have traced down the issue to the LG display. When connected to the first Thunderbolt 3 port on the display, the machine fails to recognize the external mouse and keyboard connected to the display through the USB 3.0 ports. However, when connected to the second Thunderbolt port, it recognizes them just fine.

The weird thing is that, if the machine is restarted while connected to the display through the first Thunderbolt 3 port, it will also recognize the keyboard and mouse. It only fails to recognize them if it is already powered up when connected to the display, and only if connected through the first port (but not the second).

Anyway, easy fix for me (just swap which Thunderbolt 3 port I use). Hopefully someone else finds it useful.

One further (small) update. It turns out that the problem is not linked to the specific thunderbolt 3 port in use, but to actually disconnecting the cable from the display, and reconnecting it again (which I had to do to switch ports). If the computer is connected to a cable that was already connected to the display, the display gets video and sound, but doesn't pass through any connected peripherals (such as a keyboard). If the same cable is then disconnected from the display and reconnected to it, everything works. This happens with only one of my two LG 24 displays.