Hi everyone, hope you are all doing excellent!
I just thought I’d post here to make a note of a fix I found for the map specified on the command line error. Just in case it might help anyone else in the future! 
I personally was working on a University project and I wasn’t able to get the build working because anytime I opened it, there would be this command line issue relating to a map not actually in the packaged maps and it was seemingly an unrelated one. Although I’m guessing it was referenced somewhere hidden away in the background. For me, it was attempting to look for the Open World template map. I tried all of the many different fixes and solutions I could find online and unfortunately, none of them worked.
I also tried just packaging all of the maps (which I hoped would link onto the open-world template) but that didn’t work either. Eventually this morning I did something simple of manually adding the Engine content template map to the list of maps to include for packaging section. This worked and did the trick perfectly as it now opened on a build! Was a little confused as to why packaging all maps didn’t work but this did haha!
So all in all, basically attempt to add whatever map the command line is looking for manually into the settings even if it is from the engine content folder.
One thing it didn’t do was jump to the correct default map though so after booting up the Open World template map, I just had to make it load the main menu level immediately on begin play. For anyone else I don’t know if this step will be needed in your own project.
The engine version this all relates to is Unreal 5.0.2 before I switched to Unreal 5.2. Also this was for a package to Windows. Hopefully this post is of a little help to others at some point! 
