Loop Counter Issue I Can't Figure Out

Using Arduino Programming Questions
#1

Hi--

Not a noob here, I have a few years experience programming Arduinos, but the following behavior puzzles me. I can't figure it out.

int counter;

void setup(){
  Serial.begin(9600); 
}

void loop(){
    for (counter = 25; counter >0; counter--){         
      delay(100);
      Serial.println(counter);
    }   
    while(true){
    }   
}

and the output from the above is:
8
7
6
5
4
3
2
1

What happened to 25 through 17?

The Arduino is a Pro Micro 32U4, and that is 100 % of the code, no libraries or anything, and using a clean install of the Windows IDE 1.8.13, with no changes to the libraries or other dependencies.

Any thoughts about what's causing this?

#2

Maybe the USB CDC serial connection wasn't ready yet? See Serial.IfSerial.

#3

That was exactly it, thank you!

This is the first time I've used a 32U4, so thank you for your help!

#4