Some Unicode (cjk) characters invisible in Emacs25 [Bionic]

[Sudarshan Kakoty]

I am experiencing font issues for a few specific characters.

I have attached a screenshot that shows the visual parts of the issue clearly.

using (setq-default linum-format "%4d \u2502") at ~/.emacs should produce a solid bar beside number line like the Fedora 28 doing. But both in Ubuntu (and lubuntu 18.04) and Debian Stable (even in Unstable), some characters not rendering as expected.

Link to full .emacs: https://github.com/fr0xk/workstation_setup/blob/master/conf/skel/.emacs

I tested this with fresh Fedora 28 against fresh installed Ubuntu 18.04 and lubuntu 18.04)

I also have noto fonts installed