@virtualfilmer I have been using them in 5.3 for a while managing the headache and saw your post, just jumped into 5.4 to test based on your video.
I mostly use the trackers for VR experiences but noticed you’re in the First Person Template, so my project is setup as a VR template, that’s the first difference. I initially saw the same behavior, Trackers either not showing up, or LiveLink wants to assign them LeftHand, RightHand even though nothing is designated as such.
So I have 2 trackers attached, roles Left Foot and Right Foot.
I have the following Plugins Enabled.
OpenXR
OpenXREyeTracker
OpenXRHandTracking
OpenXRViveTracker
LiveLink
LiveLinkInputDevice
LiveLinkXR
everything else is stock VR template.
Initially I see no trackers in the LiveLinkWindow when I AddSource - LiveLinkXR Source… until I hit PlayInEditor at least once. Then they appear. One stupid thing I’ve noticed in 5.3 is that (at least in VR) Trackers sometimes aren’t recognized until the HMD is worn. Same deal here, I can PIE, but unless I wear the Headset they don’t populate. If I close the project, same nothing in the list until I PIE at least once.
From that point on though they’ll stay in the list and I can save as a preset. They do function as position transform data for a static mesh with no issues, but again only while the HMD is worn. I know this is only half an answer but maybe there’s something here that might help.