chase your tail
chase (one's) tail
To take action that is ineffectual and does not lead to progress. Refers to how a dog can exhaust itself by chasing its own tail. Come on, Bill, go to sleep. You're just chasing your tail at this point, but you might have a breakthrough with the research if you take a break from it. I'm trying not to chase my tail on this project, but so many components of it are just not working out.
chase your (own) tailkeep on doing something futile. informal
chase your (own) ˈtailbe very busy but in fact achieve very little: In my first month at college I was continually chasing my own tail and being late for everything. ▶ ˈtail-chasing noun
If a dog or cat chases its tail, it runs round in circles trying to bite its own tail.