Constant Freezing and Incorrect Beatgrids

In using Rekordbox 4.0.8 on my 2015 Macbook Pro, I have run into two main issues:

- Constant freezing of the program when I try to export to a USB

- The beatgrids Rekordbox automatically sets are often totally wrong.

Any solutions? The program has been out for a while, I feel like Pioneer should have fixes for these basic issues by now.