okay so the two Minecraft tickets one MC-149518 and the other MC-142228 describe lighting issues one where skylight is under opaque blocks essentially and the other no light where light sources are. the issue I am having pertains to both but isn't, I don't think, the same as either. in this case either or both of those issues are recreated instantly after entering the chunk adjacent to the chunk that was previously fixed/and or chunks with a nether portal. so essentially after downloading the server world optimizing and erasing cache on top of running force upgrade erase cache both issues were solved but as soon as I left the adjacent chunk then reentered it used a nether portal both issues reappear as if cache maybe wasn't erased properly, or the nether portal just updates the adjacent chunk in a way that it creates those issues again. this is after moving the portal one chunk out of the original chunk not sure if that has an effect but I don't recall having the issue when the portal was in the same chunk as the light update problems. I hope I made this as clear as possible I don't have images because currently my chunks are fine as I just optimized and am trying to avoid the nether portals and recreating the issue again.