[iOS][SectionList/FlatList] List sometimes broken when scrollTo invoked upon componentDidMount

[peterjuras]

Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes

Environment

1. react-native -v: 0.46.1
2. node -v: 8.1.4
3. npm -v: 5.3.0
4. yarn --version: 0.27.5

Then, specify:

• Target Platform: iOS

• Development Operating System: macOS

• Build tools: CRNA (but also encountered the bug in normal react native project)

Steps to Reproduce

1. Run the attached sample below on iOS.
2. Refresh until bug occurs (~ usually < 10 refreshes)

Expected Behavior

List always renders all items correctly and scrolls to a list item around #80

Actual Behavior

List sometimes renders a blank screen and the list is broken. Scrolling will return to the first 10 list items, but the list will no longer render the other 990 items until another refresh.

You can check out this gif to see the bug in action.

Reproducible Demo

Please check out this CRNA sample to reproduce the bug:
https://github.com/peterjuras/rn-list-scrollTo-bug

[peterjuras]

Reopened #15697