Apple Airpods Charging Issue

Try cleaning the charging contacts gently and making sure the left earbud clicks fully into the case, since a poor seat is a common cause. Does the case itself charge normally, and does the right earbud still charge as usual?

I had the same thing with a left AirPod that just would not charge. Cleaning the contacts helped a bit, but what actually fixed it was resetting the AirPods by holding the setup button on the case for about 15 seconds until the light flashed amber, then white, and pairing them again. If it still will not charge after that, try swapping the buds between slots to see whether the problem follows the bud or stays with the case slot.

Try cleaning the charging contacts in the case and on the left AirPod, then reseat it firmly until it clicks. If that fails, reset the AirPods and pair them again. If it still will not charge, test it in another case if you can, since that helps tell whether the earbud or the case is at fault.