My puppy is barking in his crate but doesn’t want anything. Help?

I have a three month old male border collie/kelpie cross puppy, and sometimes he’ll bark in his crate, but he doesn’t want anything? I open the crate and offer food, toys, outside time, a potty break, etc. but he just stays in his crate, then when I try to close it and walk away he starts to bark again?

I don’t know what the cause could be. Judging by his behaviour, he’s not hungry or bored or lonely or in need of the bathroom. What could it be? Might it be a breed trait? I know that kelpies are very very barky dogs, and that’s good for me, I like a dog that barks and can let me know when it needs something, but it’s been confusing lately since my boy has started randomly barking and seemingly not wanting anything.

Any of you had this problem? If so, did you figure out what it was?