How do you save a checkpoint in H5 Campaign?

So I am going back and trying to finish some achievements and I want to save a particular checkpoint to come back to later and play for achievement. In the past, I was able to do so… now I can’t figure out how to save a particular point in the game. The last checkpoint will reload but when I leave the game I have to start the mission over again. I used to have 3 save slots and now they are old saves but I can’t replace them with new saves. Please help!

Update: Nevermind. I found out that I had scoring on all this time and you can’t save during scoring.
Solution: Turn off scoring during campaign in order to have the option to save the present checkpoint.