Why is it whenever I use std::ios:trunc, the stream is falsy

Question

So I have the following code:

#include <iostream>
#include <fstream>
#include <string>

void writeSingle(std::fstream &myFileStream)
{
    myFileStream.open("my_file2", std::ios::trunc);
    if (!myFileStream)
    {
        std::cout << "File not created!\n";
    }
    else
    {
        std::cout << "File created successfully!\n";
        myFileStream << "Line 1\n";
        myFileStream << "Line 2\n";
        myFileStream << "Line 3\n";
        myFileStream.close();
    }
}

int main()
{
    std::fstream myFileStream;
    writeSingle(myFileStream);
    return 0;
}

My question is, whenever I use std::ios::trunc, be it in a combination with app (std::ios::trunc | std::ios::app) and regardless to whether the file exists or not, the program ends up in the !myFileStream block. With only std::ios::out and std::ios::app the program works as expected.

Why is it so? Can someone provide at least one working example with std::ios::trunc? Thanks.