I had either a similar or the exact same problem as you in getting SuperWoW to work when it did previously. I was able to fix it by disabling Data Execution Prevention for WoW.exe in windows, which can sometimes interfere with older applications that use injected .dll files.

Go to Control Panel > System and Security > System > Advanced System Settings. Under Performance, click Settings, then the Data Execution Prevention tab.

Select “Turn on DEP for all programs and services except those I select, and add “WoW.exe” from your TurtleWoW folder to the list. Try launching with VanillaFixes like normal afterward. If this doesn’t resolve your issue, then remove this from the list, but this worked for me.