Pinegrow 5.4 problem with SASS import

Since I have installed 5.4 I get strange error messages when saving a file:

The following stylesheets were not saved - Undefined variable:"$HEADER-BG" in file stdin at 14:23

My scss file import some constants
@import “_constants.scss”;
In this file the constant $HEADER_BG is defined.
I compiled the scss file with a manually installed SASS compiler - OK.
Note thet the constant’s name is written with an underscore, while the error message used a dash instead.

@dgrabowski can you send your project or at least the SASS files to so we can investigate. We did some changes in how imports are handled in 5.4.

@matjaz Thanks for replying so quickly. I sent you the sass files and the pinegrow.json via email, but I failed to send you the archive with the complete project as the mail server did not accept the attachment.
If you need any specific files please let me know.

Thanks, got it. Will be in touch soon.