how to mask the lineEdit text with asterisks for password entry?

[ChrisW67]

Repeating yourself will not change the outcome. Doing something to try to help yourself might.

Here is the complete, small, test case you could have written to confirm the behaviour:

#include <QApplication>
#include <QLineEdit>
#include <QDebug>
 
int main(int argc, char **argv) {
  QApplication app(argc, argv);
  QLineEdit l;
  l.setEchoMode(QLineEdit::Password);
  l.show();
  qDebug() << "Should see dots" << QString(5, QChar(0x25CF)) << QString(5, QChar(0x2022));
  return app.exec();
}

#include <QApplication>
#include <QLineEdit>
#include <QDebug>

int main(int argc, char **argv) {
  QApplication app(argc, argv);
  QLineEdit l;
  l.setEchoMode(QLineEdit::Password);
  l.show();
  qDebug() << "Should see dots" << QString(5, QChar(0x25CF)) << QString(5, QChar(0x2022));
  return app.exec();
}

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Does it fail with this?

If not then the problem in your program is external to the QLineEdit.
Have you applied a style sheet? Is the text/foreground colour white?
Does your font have a glyph for Unicode code points U+25CF or U+2022 because these are selected in preference to '*' which is the fallback option.