I found the same problem on issue tracker, this means the problem has been in existence since 5.5, until the latest 2017RC is still unresolved, is this what unity deliberately designed?
Its not deliberate. Its a bug, the issue tracker shows it as still active, This means it has not been fixed yet. Higher priority bugs are dealt with over this one as it is considered a minor/cosmetic issue so can take longer to be fixed.
If this bug fixes, can release a new unity5x version? I want build wp8.1 game.
It should be backported to a patch release if its fixed before patch support ends. How is this bug preventing you from building for wp8? Its just an editor issue isn’t it?
Just this bug made me feel uncomfortable.
Finally, thank you.