DIrectX 11 / x64 Not working

I get an Exception-Error: Failed to create mutex
... if I do the admin-rights-start of the second instance of Path of Exile

after that the next Exception-Error: You may only run up to two copies of Path of Exile at one time.
... doesn' t matter if it is the second, third, ... start of the game.

after that I get another Error: The DirectX 11 client crashed on startup. Would you like to switch to the DirectX 9 client instead?
.... I choose No: Nothing will happen
.... I choose Yes: Second instance of the game will start using DirectX 9Ex


I am thankful for every information to my 'problem'.

when i start up PoE it says there are 2 instances running, there are not. right after i get a message DX11 crashed, would u like to switch to DX10. i chose no and restart PoE, then it works fine in dx11

I can play for a while then it crash with the 64x error again again and again windows is up to date. etc

It's very annoying.

I also cant play with dx11 this expansion either. Created multiple reports, topics, reddit posts, wrote to support twice, sadly noone cares. Also I saw multiple topics about it from other people.

.