[stumped]

So I think you are saying that specific library will always stop at the book in position x. A fixed number, whatever that book happens to be.
Is that the case and can you confirming by taking single entries in and out.
And is the book at position X+1 the real culprit?
What is X.
Don't worry about library size. I have seen claims of much bigger libraries than yours working ok.

Re the app. Stop and clear data reverts it to being just like a fresh install but sure, you can Remove it , reboot device , add it back. Every theory you can cross off the suspects
Lists helps narrow things down.

If laptop and cc are both using the same IP address for content server then yes they are seeing the same data. Which points the finger back at cc. Strange. Check that tablet is not running low on ram , or storage

But it stops , always? , At book X in one library , yet can scroll to ≥x in a different library