Kotlin code duplicates a line in console on its own (looping through a function without taking user input) - kotlin

Question

Let me first put the code then explain:
fun main() {
loop# while (true){
println("Input the action (add, remove, import, export, ask, exit):")
val userInput = scanner.nextLine()
when (userInput){
"add" -> add()
"remove" -> remove()
"import" -> import()
"export" -> export()
"ask" -> ask()
"exit" -> {
print("Bye bye!")
break#loop
}
}
}
}
This is the main function where the user chooses what he wants to do. First he adds some cards that contain terms and definitions as pairs, but thats irrelevant. The problem lies after that, when using the function ask().
fun ask() {
println("How many times to ask?")
for (i in 0 until scanner.nextInt()){
for ((key,value) in map){
println("Print the definition of \u0022$key\u0022:")
var userAnswer = (readLine() ?: "exit").toString()
if (userAnswer == value) {
println("Correct answer.")
continue
}
else {
loop# for ((key2,value2) in map){
if(map.containsValue(userAnswer) && userAnswer == value2){
println("Wrong answer. The correct one is \u0022$value\u0022, you've just written the definition of \u0022$key2\u0022")
break#loop
}else if (!map.containsValue(userAnswer)) {
println("Wrong answer. The correct one is \u0022$value\u0022.")
break#loop
}
}
}
}
}
}
The code works and everything, but after doing the ask() function, just when the program loops back to main(), it prints "Input the action (add, remove, import, export, ask, exit):" twice instead of once. A friend of mine told me it could be an empty input left in cache that triggers this, so that it goes once through main() without actually taking user input.
Please, if anyone has experience with this I would really appreciate it to hear and learn about it and how to prevent it, cause it hinders me from finishing the project. Would changing the way how I take in users input help?