I found that the Application Power plan rule for wowclassic.exe is being ignored due to its 'Induce Performance Mode' classification. This is because Performance Mode is also set to change the power plan, and thus the rules would have conflicted, resulting in potentially unexpected behavior.
Secondarily, Performance Mode was not being engaged because it was already on, by way of manual induction via the Process Lasso menu. I assume you clicked it on at some point? It appears so.
Manually entering Performance Mode and/or switching power plans while processes with power rules are running can result in unintended behavior.
Somehow (unclear how) you were in 'Power Saver' while in Performance Mode, so it may not have been obvious, with only the 'Performance Mode' text on the graph indicating this state.
The newly issued beta build v9.9.0.19 allows Application Power Profiles to be combined with Performance Mode on the same process. This should resolve the problem, but this adjustment is considered experimental at this time, due to the inherent rule conflict.
RESOLUTION:
* Uncheck 'Induce Performance Mode' on wowclassic.exe
* OR exit all games/apps and turn off Performance Mode if engaged (then don't engage manually again)
* OR try experimental v9.9.0.19 beta
Let me know how that goes!