Simulink cannot detect compiler for c code generation from a protected model, even thoug Matlab sees it (MinGW)

Simulink Embedded Coder cannot generate c code from a protected model.

Error message:

No supported compiler detected. A compiler is required by some simulation modes and the build process. Install a supported compiler. For options, see https://www.mathworks.com/support/compilers. After installing a supported compiler, restart MATLAB.

I have installed MinGW.

Matlab can see it:

>> mex -setup

MEX configured to use 'MinGW64 Compiler (C)' for C language compilation.

I can generate code from other models without problems.

I don't know what's inside the protected model, but the code generation settings seem to be the same as for the other models.

1) How is it possible that Matlab can see MinGW but Simulink can not?

2) What can be inside a protected model that causes this error message when trying to generate c code from it?

[Walter Roberson]

Which release?

In some releases, MinGW is not supported for some operations and VS or Intel must be used instead.

[Szkupien Bence]

R2020a

[Szkupien Bence]

The protected model was also made in R2020a.