[Reader] Reader suddenly stops fetching tag posts

[!WARNING]
This issue was discovered after https://github.com/wordpress-mobile/WordPress-Android/pull/19881 fix, since we couldn't reach the state described here before that fix. If you follow the steps to reproduce without the commits in that PR, you won't be able to reproduce it.

https://github.com/wordpress-mobile/WordPress-Android/assets/14964993/e51092be-2ece-4ca0-a889-b5e334f4be42

Doesn't seem related to https://github.com/wordpress-mobile/WordPress-Android/pull/19881 since in that case we were still fetching the posts, and in this case fetching posts is not even triggered (I've debugged and fetch posts is not called). The progress UI is not even shown, which makes me think it might be UI related. Also, I've checked web and there were many more posts with the tag seen in the video that we were not fetching.

Expected behavior

We should continue to fetch tag posts when user scrolls down the list.

Actual behavior

At some point we stop fetching new tag posts when user scrolls down the list.

Steps to reproduce the behavior

• Install JP and sign in
• Open "My Site"
• Tap on "View all responses" in blogging prompts card
• Verify if 7 items are fetched each time we fetch a new page.

Tested on [device], Android [version], JPAndroid / WPAndroid [version]

Start at the Reader flow reached through My Site > View all responses, reproduce with JP signed in, and inspect why scrolling stops triggering post fetching. Done means the list continues fetching tag posts as the user scrolls, with 7 items fetched for each new page.