Reader Mode settings do not work correctly

Steps to reproduce:

1. Load a webpage (not in Reader mode)
2. In the toolbar, click the Settings button. A popup appears with site-specific settings.
3. Tick the box to enable Reader mode for the website.
4. As expected, the webpage is now displayed in Reader mode.
5. Click the settings button in the toolbar again to make the site-specific settings go away.
6. Click the settings button in the toolbar again, to display the site-specific settings.
7. Notice that checkbox for Reader mode, which you ticked in step 3, is not ticked.
8. Tick the box to enable Reader mode for the website.
9. Bizarrely, this takes the webpage out of Reader mode.

Expected behavior:
In step 7, the checkbox for Reader mode should be ticked. (The box was ticked in step 3, and that should stick.)
In steps 8-9, ticking the box to enable Reader mode should not disable Reader mode.

Orion, OS version; hardware type:
Orion 0.99.115.3-beta (WebKit 614.1.12)
MacOS Catalina 10.5.7
MacBook Air 2020 (Intel)