Windows 64-bit, drivers up to date, happens on default settings without GZDoom ini,
latest g4.8pre-369-g0a208597c from drd and GZDoom 4.7.1.
In normal gameplay this pretty much never happen(?) but in some instances in a random fashion:
some fireballs go fully unlighted,
some fireballs are lighted from the start,
some unlighted fireballs snap lights on while in midair.
Here's a test map and a demo file recorded on that latest g4.8pre-369-g0a208597c
but it plays on 4.7.1 with the same results.
https://www.dropbox.com/s/tw35dhf3ya8hl ... n.zip?dl=1
Play the demo with:
gzdoom.exe -iwad doom2.wad -file lights.pk3 imp+baron.wad -playdemo imp+baron.lmp