Can not switch from en_US.US-ASCII to en_US.UTF8

I am using many non ASCII characters in my filenames and up untill now everyone worked correctly. I am running **openSUSE Tumbleweed** and currently updated to the **20191118**. I have noticed that my locale output is now showing

LANG=en_US.US-ASCII
LC_CTYPE="C"
LC_NUMERIC="C"
LC_TIME="C"
LC_COLLATE="C"
LC_MONETARY="C"
LC_MESSAGES="C"
LC_PAPER="C"
LC_NAME="C"
LC_ADDRESS="C"
LC_TELEPHONE="C"
LC_MEASUREMENT="C"
LC_IDENTIFICATION="C"
LC_ALL=C

I have tried to change settings by using localectl set-locale LANG="en_US.utf-8" but no success, since after the update they seem to reset. I am not sure whether this is an actual bug somewhere (in Dolphin, KDE / Plasma, openSUSE, etc.) or some settings have changed?