You have to push the Turn On button if you want ThrottleStop to do anything with the CPU multiplier.
Did you open up the Limit Reasons window to look for any reasons for throttling while your CPU was stuck at the 12 multiplier?
Check the High Performance box near the top left of ThrottleStop's main window to switch to the Windows High Performance power plan. This keeps the CPU at its maximum speed regardless of load.
Check the Set Multiplier box so this data is sent to the CPU and press the Turn On button at the bottom. The ThrottleStop title bar should not show the word Monitoring in it.
Clear the BD PROCHOT box.
In the Turbo Power Limits window I would clear the Disable Controls box in the Power Limit Controls section. I would clear both Clamp options and I would increase PL1 and PL2 to at least 150W or 200W. The default 90W PL1 setting is not much for an 8 core CPU.
Turn on the ThrottleStop Log File option and go play a game or do something with your computer for at least 15 minutes. When done testing, exit ThrottleStop so it can finalize the log file. You can copy and paste the log file data to