RadioButton Returns Nil for Values with Diacritics

I am encountering an issue when using the Debenu QuickPDF library on iOS. Specifically, when a RadioButton field has a value containing diacritics (e.g., “Äpfel”), the library returns nil for the field’s value. For comparison, fields with plain values (e.g., “Apfel”) are handled correctly and return the expected value.

if type == 4 {
    let count = _dqpl.getFormFieldKidCount(id)
    for i in 1...count {
        let subId = _dqpl.getFormFieldKidTempIndex(id, i)
        if let title = _dqpl.getFormFieldTitle(subId) {
            _logger.debug("\(_loggerPrefix),Field \(i): value is \(title)")
        } else {
            _logger.warning("\(_loggerPrefix),Field \(i) value is nil")
        }

Here are the log details:

2025-01-27 10:59:15.256 💛 WARNING: Document interface, Field 1 value is nil

2025-01-27 10:59:15.256 💚 DEBUG: Document interface, Field 2: value is Apfel

I tried a lot of different API functions to get the value (not only getFormFieldTitle(id)) but nothing returns the value with diacritics and I have a validation for value to exist before rendering an acrofield.

Could you please confirm if this is a known limitation or suggest any workaround?
I am using Quick PDF Library Version 16.14

Thank you!