If I press to rebuild the achievements, it will also recount and all members will automatically be awarded ranks and badges based on past posts? Or all members ranks will all be set to 0 and only future content will influence their ranks?

Just wanted to confirm before pressing the button. I presume it is the first of the options above (hopefully) 

Thank you in advance

It will recount and re-assign achievements based on past content/data. It will not reset your members achievements back to 0 and make them start all over again with future content.

30 minutes ago, Jim M said:

It will recount and re-assign achievements based on past content/data. It will not reset your members achievements back to 0 and make them start all over again with future content.

Awesome, great @Jim M. Exactly what I was looking for. Thanks.