Hello
This is annoying, a lightwave scene with lots of ies lights (and some used as texture emission)
Whenever I close and reopen the scene, there is no ies active anymore. What I mean is that if I look at the lightwave texture panel for the lights, the name of the ies is still here but the icon is black and the light renders nothing. If I click on the path of the ies, It opens in the right folder, I just have to hit enter and the icon displays the ies appearance , light works now as expected. Same with emiters in the surface node editor.
I looks like clicking and reloading the ies is mandatory because the path somehow is not refreshing when loading the scene.
This is with Lightwave 2015.3 (had to use It to match a team job) but I'll check with Lightwave 2020 as soon as I can.