Your method works till these days!!!
What I Did:
I tried manually writting the ini file. But it still fails. I thought I’ll give up making plugins and develop scripts in base game. Until I saw your post.
So I rolled back ini changes, deleted {ProjectName}/Saved/Config’s files (And generated project files and building project again to make sure every possible change occurs) and boom, the changes popped up 
My Thoughts:
I found out no game engine in the world can be perfect.
I’ve used many game engines before. Including Unity I left for it’s pricing structure that causes bankruptchy. But no engine is perfect. Weather it crashes a lot, has a bug, low features etc. But you can still find the best (Not Perfect) out. To my attitude, I really think Unreal Engine is the best. Of Course, Flax Engine has better and faster graphical capability. But biggest disadvantage being graphical powerhouse is Flax Engine had not as developed so many handy features as Unreal Engine did!!!
Even if Unreal Engine can’t be called the perfect engine (Nor that Unity is), but it’s the best game engine, contains almost all in one game engine/tool to make games properly, in best practices.