When you load a page it makes a copy of the current block list in memory for that page and when another page updates the database it does so by writing the modified copy to the extension which stores it in the extension's local storage.

If an a page was loaded in the past, and you have since interacted with the extension via another tab, interacting with that page will revert the block list to what it was when that page was loaded. Losing the updates which have been done since.