SCSS file not found - cannot add/customize/override scss for a single site

[specialistaweb]

Bug Report

Adding this typoscipt:

page.includeCSS {
 theme-999 = fileadmin/template-site/common.scss
}

Expected behavior

This is a fast and simple way to add custom SCSS files processed with the bootstrap SCSS files

Actual behavior

TYPO3 v. 16.0.0 with boostrap package 16.0.0 return this error

`/var/www/example.com/web/FAL:1:/template-site/common.scss` file not found for @import: /var/www/example.com/web/FAL:1:/template-site/common.scss on line 1, at column 0

Notes

• running this code under TYPO3 v.12-13 and previous boostrap, all is ok and fine
• as you can see above, instead to use the folder name 'fileadmin' the compiler resolved with FAL:1:
• obviously the files common.scss exist and the document is accessible
• if you change the line: theme-999 = fileadmin/template-site/common.scss with theme-999 = FILE:fileadmin/template-site/common.scss no errors are displayed but the file is not considered anyway

Versions

TYPO3 Version 14.0.2
Classic mode
webserver Apache
PHP 8.2.30
MySQL 10.11.14-MariaDB-0+deb12u2
Production
o.s. Linux 6.1.0-42-amd64
bootstrap packge 16.0.0