Why React Native RNFS's copyFile() cannot access to existing file on iOS?

I'm trying to access and copy a file from "/Documents" folder (on ios simulator) with RNFS but while .exists() can find the file, .copyFile() returns error as "The file 'temp.jpg' doesn't exists"

Why that can happen?

Here is my source file path (and also I can access it with image components):

Also adding "file://" to path doesn't work too.

/Users/myusername/Library/Developer/CoreSimulator/Devices/D305Z9A4-6C67-4DFE-A07D-1EF4D0302B87/data/Containers/Data/Application/B933EF45-391F-4882-986F-92B5430823D0/Documents/temp.jpg

Here is my code snippet, newlyCroppedImagePath is the path above. exists() returns correct result but .copyFile() returns "doesn't exists"

    RNFS.exists(newlyCroppedImagePath)
    .then((success) => {
        console.log('File Exists!'); // <--- here RNFS can read the file and returns this
    })
    .catch((err) => {
      console.log("Exists Error: " + err.message);
    });

    RNFS.copyFile(newlyCroppedImagePath, tmpFilePath)
    .then((success) => {
        console.log('file moved!');

    })
    .catch((err) => {
      console.log("Error: " + err.message); // <--- but copyFile returns "doesn't exists" error for temp.jpg
    });