Flathub version (installed via Discover) does not open in Manjaro (Arch)

[mysigninname]

• SolveSpace version: 3.1 (released 2022.06.01)
• Operating system:** Manjaro 6.5.0-1

Expected behaviour:

Expecting the application to start

Actual behavior:

Application does not start

Additional information:

none at this time

[dgramop]

Can you try invoking it from the terminal? Is there anything printed to the console?

[mysigninname]

On running com.solvespace.SolveSpace it says...

Sorry, only UTF-8 locales are supported.

[froqstar]

Same here

➜ ~ flatpak run com.solvespace.SolveSpace
Sorry, only UTF-8 locales are supported.
➜ ~ localectl
System Locale: LANG=en_US.UTF-8
LC_NUMERIC=de_DE.UTF-8
LC_TIME=de_DE.UTF-8
LC_MONETARY=de_DE.UTF-8
LC_PAPER=de_DE.UTF-8
LC_MEASUREMENT=de_DE.UTF-8
VC Keymap: us
X11 Layout: us
X11 Model: pc105
➜ ~

[froqstar]

I remember from a past life that if I patch this locale check out and rebuild the flatpak myself, SolveSpace runs just fine.
What is this check supposed to prevent?