TextKit 2: Applying ParagraphStyle in custom NSTextParagraph leads to cursor position being off - swift

Question

In a NSTextContentStorageDelegate I use textContentStorage(_ textContentStorage: NSTextContentStorage, textParagraphWith range: NSRange) -> NSTextParagraph? to serve custom NSTextParagraphs. In these I set a paragraph style to the attributed string. The head indent of this paragraph style equals the amount of whitespace at the beginning of the string. This leads to an aligned indent when the line is wrapped in the text view.
This works. However, in some cases (not always) the caret will not move to the end of the wrapped line. It is stuck before and does not reflect the correct insertion point, a bit like so:
xxx xx xx
xxx xx Ixx <- does not move to the last characters
I add the code below. Does anybody have an idea why this may happen? All help is greatly appreciated.
This is the code:
extension HighlightTextEditor.Coordinator : NSTextContentStorageDelegate{
func textContentStorage(_ textContentStorage: NSTextContentStorage, textParagraphWith range: NSRange) -> NSTextParagraph? {
var paragraphWithDisplayAttributes: NSTextParagraph? = nil
let textWithDisplayAttributes = textContentStorage.textStorage!.attributedSubstring(from: range)
var finalString: NSMutableAttributedString? = nil
if parent.lineBreakStrategy != .none{
var indentLength: CGFloat = 0
//find the first index which is not a whitespace
if let endIndex = textWithDisplayAttributes.string.firstIndex(where: {!$0.isWhitespace}){
if endIndex != textWithDisplayAttributes.string.startIndex{
//calculate a range from start to first non-whitespace character and convert to NSRange
let range: Range = textWithDisplayAttributes.string.startIndex..<endIndex
let convertedRange = NSRange(range, in: textWithDisplayAttributes.string)
//get a substring with only the whitespace characters
var measureString: NSAttributedString?
if parent.lineBreakStrategy == .aligned{
measureString = textWithDisplayAttributes.attributedSubstring(from: convertedRange)
} else if parent.lineBreakStrategy == .indented{
measureString = textWithDisplayAttributes.attributedSubstring(from: convertedRange) + NSAttributedString(string: " ")
}
//get the size of the substring and calcualte the index lengths depending on the strategy
indentLength = measureString?.size().width ?? 0
//create the paragraphStyle and set the headIndent either to the length or 0, if not calculated
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.headIndent = indentLength
//add the paragraphstyle to textWithDisplayAttributes
finalString = NSMutableAttributedString(attributedString: textWithDisplayAttributes)
if let finalString = finalString{
finalString.addAttribute(.paragraphStyle, value: paragraphStyle, range: NSRange(location: 0, length: finalString.length))
//create the new NSTextPara with the final string
paragraphWithDisplayAttributes = NSTextParagraph(attributedString: finalString)
}
}
}
}
return paragraphWithDisplayAttributes
}