This bug is known and is reported here: Audacity Recovery does NOT honor user’s selection to discard broken project. #1485
If, as waxcylinder suggests, you have the “envelope problem”, then I suggest that you run AudacityRescue one time to clean up the damage. See: 3.0.3 experiencing extreme slowdown and is Not Responding - #18 by jademan
Upgrading to 3.0.4/5 will keep this problem from recurring.