Version: 1.6.18.0
Frequency: Consistently
Bug description:
SU4 has introduced a rounding error to the position of airport beacons. We noticed them flashing sporadically while illuminated, which was the result of them jittering around on a cubic grid as you move your camera around. Video here
Martyn - Just Flight
Confirmed (also with 1.6.19.0).
I have seen crazy “rounding errors” especially along the vertical axis (I’m talking 10s of meters!) in cases where the associated object consists of a single node and placed with ground offset (I use this technique frequently as a quick-and-dirty way to add heliport beacons to third party scenery - mainly hospital helipads).
Here’s my “beacon_dummy.gltf” object if anyone wants to reproduce:
beacon_dummy.zip (339 Bytes).
I can see huge jittering (or "“clamping”) steps when in dev mode and changing the vertical offset of the beacon object.
I suspect dynamic terrain LOD might play a role here and making the issue worse.
Based on my testing this is now fixed in the SU4 1.6.21.0 beta.
Hello,
Thank you for the feedback.
Indeed, it’s fixed in SU4 flighting 1.6.21.0 
Regards,
Boris