Jobs and Experts crashing site

currently deleted Jobs and Pros via SFTP to get the site back up.

i am trying to recall exactly when it all came crashing down,
i believe it was when saving add ons in "private messaging" in order to use "private messaging" with Jobs and Experts.

i would have activated a few add ons before hitting save changes so i cannot pin point which add on may cause it.

i believe i had this problem on another site previously and possibly may have happened when i selected "bbpress" add on for "private messaging".

i also tried deleting Jobs and Experts then deactivating bbpress, then install Jobs and Experts again to see if it was indeed Jobs and Experts alone and not bbpress but same problem, basically i tried troubleshooting various options but currently Jobs and Experts seems to not be able to install through admin nor SFTP. i tried using both replace and merge on different occasions but no dice.

another thing, even before setting up Jobs and Experts, i was continuously getting the nagging notice from "private messaging to change settings and even though i did set inbox page the message would not go away.(screenshot)

i am out of ideas,
Support access granted.
i will not hesitate to provide SFTP access if required to properly get to root cause.

also i initially installed the "private messaging" plugin through wpmudev dashboard so i don't know if having the plugin activated as well as activating the add on in Jobs and Experts could have caused a conflict. ???

just trying to provide as much info as possible.

any kind assistance would be greatly appreciated because as i mentioned this is not the first time i have encountered this problem.

kind regards and much thanks again in advance.