When clicking Build & Test, SDK packs the world into a .vrcw file in
c:\Users\[username]\AppData\LocalLow\VRChat\VRChat\Worlds\
When using VRC Quick Launcher, it reads the files inside of that folder and creates a list of worlds that you can run locally.
Looks like since 3.7.6 the .vrcw file has its name lowercased, like
scene-standalonewindows64-world_name.vrcw
and for some reason VRCQL doesn't recognize that as a valid world name.
If you rename it to
scene-StandaloneWindows64-world_name.vrcw
then it appears in VRCQL just fine.
PS: world's name is lowercased too, while it wasn't before, although it works for VRCQL either way.