The only common session between PCMS and PS is the UserGroupID.
The fix to this would be not to set the UserGroupID when logging in to PS.
You can not set the UserGroupID by modifying the following lines of code from the users_login.php page in PowerStore:
"sessionColumns" => explode($WA_Auth_Separator,"UserID".$WA_Auth_Separator."UserEmailVerified".$WA_Auth_Separator."UserEmail".$WA_Auth_Separator."UserGroupID"),
"sessionNames" => explode($WA_Auth_Separator,"UserID".$WA_Auth_Separator."UserEmailVerified".$WA_Auth_Separator."UserEmail".$WA_Auth_Separator."UserGroupID"),
and change them to:
"sessionColumns" => explode($WA_Auth_Separator,"UserID".$WA_Auth_Separator."UserEmailVerified".$WA_Auth_Separator."UserEmail"),
"sessionNames" => explode($WA_Auth_Separator,"UserID".$WA_Auth_Separator."UserEmailVerified".$WA_Auth_Separator."UserEmail"),