Please double check you have Collisions disabled (under Distribution Map rollout) and the Boundary Checking is set to Point - as the size of the object is changing during the animation (under Areas rollout). Attaching screenshots.
If the issue persist, please send us a simplified scene (containing problematic objects) to email@example.com. Also please specify which version of 3ds Max and renderer are you using. For large files, please use a web sharing service as WeTransfer or Dropbox. We'll analyse it to identify what's causing the problem and hopefully find the solution soon. Sorry for any inconvenience caused.