Both the app and the website have some issues when you change the sequence of chapters, or insert or remove chapters, for as long as I can remember.
There’s no easy solution. I stopped writing or re-arranging in Wattpad itself. These days I have two Google Docs files, one containing all chapters / parts ‘done’, one with the current chapter / part in progress (to speed things up when editing on a slow device). I just copy a chapter into Wattpad every time I’m done.
I’ve added this to the ‘preface’ of my novel-under-construction:
Wattpad readers please be aware: Wattpad is a great platform but has some synchronization issues. This especially happens when I update an older chapter, or change the sequence. (Please Wattpad devs, fix this, or give us a ‘manual sync’ button…)
If you see an incomplete chapter, damaged text, or if you receive a notification that an older chapter has been revised and you want to make sure you have the latest version of this book, then please do the following:
When using a browser on a PC: hit Shift + Refresh, or clear your cache
On an Android device: go to Android Settings / Apps / Wattpad / Storage, and Clear Data. This will force Wattpad to reload everything in your library. You will have to log in again.