Quick answer
If this stops working offline, check whether the file is local, whether an optional feature needs internet, and whether Android removed cached data.
Do not assume the book itself is broken.
Check optional downloads
A voice or dictionary may need a separate download even when the book is local.
Test another local file
If another local file works offline, the first file or its source may be the problem.
If the first fix does not work
Try another known-good notes and highlights kept on your phone example. If the second one works, the first file or item is probably the problem. If both fail in the same way, the app, phone, or setting is more likely.
Detailed troubleshooting checklist
Work through the problem in this order: first check notes and highlights kept on your phone itself, then the app, then Android or the device. Keeping that order prevents you from changing many things when only one part is wrong.
- Change one setting at a time.
Verify the fix before you keep it
For “Notes and highlights kept on your phone: common problems and simple fixes”, a fix is worth keeping only when you can close the app, reopen the same material, and repeat the task without the problem returning.
- For “Notes and highlights kept on your phone: common problems and simple fixes”, if privacy matters, separate local reading behavior from optional network features and test each one deliberately.
- Open the item, close the reader, and reopen it while still offline so cached screens are not mistaken for true offline access.
- Keep important source files in a folder you control instead of relying on a temporary download location.
What a good result looks like
For “Notes and highlights kept on your phone: common problems and simple fixes”, offline reading is dependable when the full task still works after a fresh reopen with the network disabled and you know which optional features need internet.
For this guide, stop adjusting once the workflow for “Notes and highlights kept on your phone: common problems and simple fixes” is clear, repeatable, and easier than the problem you started with.