I listed a dual enrollment course on the common app for second semester senior year but because it was dual enrollment I wasn’t able get into it (all the seats filled up). I never started the course and it was never on my transcript I had just thought I might be taking it if I could get into it. Do I still need to let colleges know I ended up not taking the class?
Yes, I would let them know.
The same thing happened to my daughter and she informed all of her schools about it. So, yes, you should do that.