Had an initial contact with a recruiter. Set up an initial phone screening and was stood up. Learned later that the director was absent from work that day, and no one had the courtesy to notify me. Rescheduled the initial tech interview.

Had one coding problem on an online coding platform. Solved it and passed tests on the first run.

Never heard back, even after emailing and requesting feedback one way or another. In general, a fairly unprofessional way to conduct recruiting.

If you are going to waste someone's time, at least have the courtesy to formally tell them you have decided against moving forward, even if you don't want to give feedback.

Decline to state the nature of the coding problem.