File empty after writing to file obtained with classLoader

My simple program is as follows:

import java.io.File;
import java.io.IOException;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;

public class ProgressionYAMLUtil {
	private final static File PROGRESSFILE_FILE = getProgressionFile();
	
	public static Boolean write(Progression progression) 
	{
		ObjectMapper objectMapper = new ObjectMapper(new YAMLFactory());
		try {
			objectMapper.writeValue(PROGRESSFILE_FILE, progression);
		} catch (IOException e) {
			e.printStackTrace();
			return false;
		}
		return true;
	}
	
	public static Progression read() 
	{
		ObjectMapper objectMapper = new ObjectMapper(new YAMLFactory());
		
		Progression progression = null;
		try {
			progression = objectMapper.readValue(PROGRESSFILE_FILE, Progression.class);
		} catch (IOException e) {
			e.printStackTrace();
			return null;
		}
		
		return progression;
	}
	
	private static File getProgressionFile() {
		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
		File file = new File(classLoader.getResource("progress.yaml").getFile());
		return file;
	}
	
	public static void main(String[] args) {
		
		Progression p1 = new Progression("foo");
		
		p1.newRun(2);
		p1.newRun(9);
		p1.newRun(11);
		
		System.out.println("WRITE");
		System.out.println(p1);
		
		Boolean b = write(p1);
		System.out.println("write successfull: " + b);
		
		
		System.out.println("READ");
		Progression p2 = read();
		System.out.println(p2);
	}
}

For some reason after running this code, my progress.yaml file is still empty. The program works fine and the printout is very much expected:

WRITE
Progression: foo

0 - 2
1 - 9
2 - 11

write successfull: true

READ
Progression: foo

0 - 2
1 - 9
2 - 11

If I run the main method without the write-block, the program still reads successfully. How can it read content that isn't there? I looked up the internet whether there are some file cache I should clear to get a better understanding of the issue, but I came out short.

If I change the writeValue statement in the write method to objectMapper.writeValue(new File("src/main/resources/progress.yaml"), progression);, that is obtaining the file without classLoader, the program writes to file and the changes are observable.

How come this happens? Thanks for help