gen_db appimage not working, can't login

[farsighter]

Although I'm getting a login code in TG after entering my number, gen.db treats me as someone who's registering a new TG account rather than making a simple login. It looks like this:

Enter phone number: ********
Enter your first name: ****
Enter your last name: ****
Enter authentication code: *****
Error: error {
  code = 400
  message = "PHONE_NUMBER_OCCUPIED"
}
Enter your first name:

Tested with two different Telegram accounts.
About 2 years ago it worked nicely but not anymore. Can this be fixed please?