Importing from multiple import sources

[log1c]

@slasse

but they throw an error:
Uncaught Error: Call to undefined function mb_strtolower() in /usr/share/icingaweb2/modules/director/library/Director/PropertyModifier/PropertyModifierLowercase.php:11

Check if you have the mbstring extension for php installed (e.g. php-mbstring for Ubuntu/Debian).
If not, install it and restart the webserver and/or php.