Required $SOPC_KIT_NIOS2 Environmental Variable is not set

Hi,

I'm trying to get the Nios II Eclipse toolchain to work on a Windows 10 machine. But the New Project wizard (File -> New -> Nios II Application and BSP from Template) does fail with the error:

Executing: wsl ./create-this-app --no-make (C:\some\directory\projectname\qsys\software\test_software)
Required $SOPC_KIT_NIOS2 Environmental Variable is not set!

I've set the SOPC_KIT_NIOS2 variable to "C:\intelFPGA_pro\19.2\nios2eds" both on Windows and the WSL Linux (Ubuntu 18.04 LTS) and also in the Eclipse settings (C/C++ -> Build -> Environment). But the error still occurs.

Did I miss something?

Or is there a way to set the Nios II toolchain to use Cygwin instead of wsl?

Thanks

Edit:

I could narrow the problem to the wsl command:

bash -c "echo $SOPC_KIT_NIOS2"

outputs the environment variable correctly, but

wsl echo $SOPC_KIT_NIOS2

can't find it. Sadly the generated scripts use the wsl command...

How can this be resolved?