log4j 2 used with Payara 4 does not create logs

Question

I'm currently trying to use log4j 2 within an .ear that gets deployed in a Payara application server version 4.1.2. My problem is that nothing gets logged, neither in the console nor in a logfile. The logfile "app.log" I defined in the log4j2.xml doesn't exist anywhere on my machine after calling the REST endpoint where I use log4j2. Does anyone have a clue what could be the problem?

Entries in my pom:

        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
            <version>2.13.3</version>
        </dependency>

        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.13.3</version>
        </dependency>

my log4j2.xml located in src/main/resources:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
        </Console>

        <File name="LogToFile" fileName="logs/app.log">
            <PatternLayout>
                <Pattern>%d %p %c{1.} [%t] %m%n</Pattern>
            </PatternLayout>
        </File>

    </Appenders>

    <Loggers>
        <Logger name="package.package" level="info" additivity="false">
            <AppenderRef ref="LogToFile"/>
        </Logger>

        <Root level="error">
            <AppenderRef ref="Console"/>
            <AppenderRef ref="LogToFile"/>
        </Root>
    </Loggers>
</Configuration>

I'm using log4j 2 like the following as it's described in many instructions online. It's used inside a REST controller, but I removed the irrelevant parts of the code.

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class App {
    public static final Logger LOGGER = LogManager.getLogger(App.class);

    public Response start() {
        LOGGER.info("START PROCESS");

        ...

        LOGGER.info("PROCESS FINISHED");
        return Response.status(...).entity(...).build();
    }
}

When doing my research I found the following thread: https://stackoverflow.com/a/61676705/12755770 But it's about Payara 5. I created the system property fish.payara.classloading.delegate=false anyway but without success.