Font Rendering Issues

Hey Folks,

I have problem with some characters. One Example is for Example 0x27FC. I have
installed a font from
https://www.fileformat.info/info/unicode/char/27fc/fontsupport.htm that should
render the font. But I still get the box with the number.

To reproduce this issues:

C-x 8 d RET 27FC RET

Which produces this: ⟼

I normaly use doom-emacs¹ where this happens, but also when I start emacs with
-Q the character won't render.

I'm using the Emails 26.1 build from:

 https://ftp.gnu.org/pub/gnu/emacs/windows/emacs-26/

Any ideas what might be causing this?

Greetings

Tim

¹ https://github.com/hlissner/doom-emacs/