So, to get me on the same page, I need to clone 4.11 project via launcher, quit, remove Saved/ folder in my project, start launcher again and load 4.11 project with 4.12, then convert it on the spot and I should be good to go?
By rename i mean F2 in windows explorer to rename project folder. Since you created project copy, folder name is not equal to projects ini info, you can fix it by hands getting into some ini files and changing path. Or you can just rename folder to anything, load project, close and rename back.
Look the easy way is open the 4.12 select your 4.11 project then will say something about create a copy him auto create the copy after the project open, close the engine, go to the created folder “nameofproject 4.12” and remove the saved folder or rename it to SavedOld, that is the more easy way. And open another time, but this time the 4.12 version created.