Global variables not behaving like global variables?

I have a large script where I define const sessionWidth = '5.1' right at the top of the script. It's never redeclared anywhere in the script.
However I have had numerous issues with the sessionWidth variable not making it into functions and forcing me to pass it on through every function and sub-function.
Are there situations where global variables don't behave global? I have an example below where sessionWidth was 'undefined' , whereas a different global worked, but it has happened across multiple functions.

With the below script when I was debugging, I had the script log the value of sessionWidth when it was inside the function function createStemFXAuxes,
i.e. log(`basePresetPath: ${basePresetPath}, sessionWidth: ${sessionWidth}`)
It's result was basePresetPath: Mix Templates, sessionWidth: undefined

Here's some of the script:

//Global variables at top of script
const sessionWidth = 'Stereo'; //'Stereo', '5.1' or '7.1'
const basePresetPath = 'Mix Templates'

function main(){

//////some other code here

log('Starting Stem FX setup...');
        try {
            processStemFX(stemNames, sessionWidth); //if sessionWidth not passed in, createStemFXAuxes fails
            log('Stem FX setup completed.');
        } catch (error) {
            log(`Error during Stem FX setup: ${error}`);
            throw error; // Abort the script
        }

//code continues...
}

function processStemFX(stemNames) { //if sessionWidth not passed in, createStemFXAuxes fails
    log(` At start of processStemFX the path is: basePresetPath: ${basePresetPath}, sessionWidth: ${sessionWidth}`);

    // Select only the last Stem Aux track to prepare for FX Auxes
    const lastStemAuxTrack = `${stemNames[stemNames.length - 1]} Aux`;
    sf.ui.proTools.trackSelectByName({ names: [lastStemAuxTrack] });

    // Log the session width before any calls
    log(`sessionWidth before calling createStemFXAuxes: ${sessionWidth}`);

    // Execute the sequence of FX setup steps
    log(` Right before createStemFXAuxes the path is: basePresetPath: ${basePresetPath}, sessionWidth: ${sessionWidth}`);

    createStemFXAuxes(stemNames, sessionWidth);
    
}

// Function to create and rename Stem FX Auxes using batch track rename functionality
function createStemFXAuxes(stemNames) {
    // Construct the full path for the Track Preset
    const presetPath = [basePresetPath, sessionWidth, `${sessionWidth} Default Stem FX`];
    
    // Log the constructed path for verification
    log(`Attempting to load Track Preset from path: ${presetPath.join(' > ')}`);  // Logged: Attempting to load Track Preset from path: Mix Templates >  > undefined Default Stem FX
    log(`basePresetPath: ${basePresetPath}, sessionWidth: ${sessionWidth}`); // Logged: basePresetPath: Mix Templates, sessionWidth: undefined

    // Attempt to create the track preset
    try {
        createTrackPreset(presetPath, stemNames.length.toString());
    } catch (error) {
        log(`Error loading Track Preset: ${error}`); // log result: Error loading Track Preset: Error: PopupMenuSelectAction
    }

    sf.ui.proTools.waitForNoModals();
    sf.ui.proTools.invalidate();

 //further scripting related to renaming the newly created tracks...

 
}
}