Just happened to me. Same circumstances. I was flying with elytra and entering newly generated areas, new chunks eventually stopped loading. Hoping exiting and reloading would fix it, I tried to save and exit. Game is still stuck on "Saving World" screen as I type this.
Confirmed for release 1.14. Once the guardian sounds reach a certain threshold (constant loop), they persist even after I travel thousands of blocks away. Only exiting and re-entering the world seems to clear the sound loop.
Uploaded. Unfortunately, I've never screen recorded before, so I exited the game to make sure it was working. When I started it back up, the Ender Dragon went from half-health to full! Maybe another bug? I'll try to upload a video later of the dragon behaving improperly in creative.
EDIT: as soon as I posted this and rejoined the fight, the dragon started doing tight circles, and didn't stop until it was dead.
Was able to replicate this on a creative world (alternatating with survival), but ender dragon was acting normally during a survival (no cheats) fight immediately afterward. Inconsistent.
Seems to be present with the new cave generation in 21w06a