The whitelisting is working for me. Please open an issue at https://github.com/kkapsner/CanvasBlocker/issues with your specific problem and your setting.

I mostly use default settings and have no whitelist defined. Please also mention the web sites that break in your issue.

How the whitelist button can be found is explained here for example: https://github.com/kkapsner/CanvasBlocker/issues/330

PS: the UI is a topic I want to tackle in the near future.