When you see changes in your EPMV, there can be many reasons as to why this has occurred. I recommend taking a look through this Support article as a checklist to help you discover the reason behind your EPMV change.
I also recommend that you check out this interactive article for additional insights into how you can improve your EPMV.
If you are still having trouble determining why this has happened, you can also feel free to reach out to our Support team to take another look.