- NPCScan_Overlay does not work for Legion and BfA rares, and to get it to work for older content you will need to read its file contents (might have to some scrolling through pages at this point) to find the fix. You can find the comments by right-clicking NPCScan_Overlay in the Twitch App and going to the webpage.
- Prepend C_Map. to SetMapByID on line 701 in NPCScan.Overlay\Overlay.lua so it reads C_Map.SetMapByID
- Do the same thing to line 250 of RareSpawnOverlay\RSO-MapManager.lua so it reads C_Map.GetCurrentMapContinent
I can't guarantee any of these fixes will get either addon working; I'm merely pointing out some fixes.