What computer operating system is your Premiere Elements 12 running on? Be sure to update 12 to 12.1 from the opened project's Help Menu/Update.
The appearance of the Sound Effects in the just installed program has been known to lag behind the installation of the program. So, often it is a waiting matter which depends on the speed of the Internet connect and the status of the Adobe Server. Leave the program open as you wait. Audio Tab/Sound Effects is the only place to access the Sound Effects. They should be "staggering" in view one at a time.
Also, make sure that you have right clicked the Premiere Elements 12/12.1's desktop icon, selected and applied Run As Administrator besides running the program from a User Account with Administrative Privileges.
Let us know the results and then we will decide what next.
Thanks for the follow up with the good news that all is OK with the Premiere Elements 12/12.1 Sound Effects now.