Unable to Scroll to the Bottom of Long Posts

[mchowning]

Description

When scrolling to the bottom of a very long post, the block list gets "reset" and returns me to the beginning of the post. This essentially makes it impossible to scroll to the end of a long post.

It feels like both Android and iOS should have this issue, but I have only been able to reproduce this issue on Android.

I've found it easier to reproduce this issue on slower builds (i.e., the demo app or a debuggable WordPress app build). The faster the build, the longer the post I seem to need to recreate the issue.

Step-by-step reproduction instructions

1. Open a long post (500 paragraphs should be more than enough)
2. Quickly scroll to the bottom of the post (if the bug doesn't occur scroll back to the middle of the post and then back to the bottom again until the bug occurs)
3. Observe that the scrolling will stop and you will suddenly be back at the top of the post.

Expected behaviour

Scrolling through the post should be fluid and not return you to the top of the post

Actual behaviour

On long posts, you are sometimes returned to the start of the post.

Screenshots or screen recording

scroll_to_top_bug.mp4

This screen recording is with the WPAndroid 19.9-rc-1 release build.

Device information

• Device: Pixel 3 and Pixel 6 Pro
• Operating system: Android 12
• WordPress app version: 19.9-rc-1 (I have not been able to recreate this issue on 19.8)

[mchowning]

I can "fix" this issue by commenting out the CellRendererComponent prop within our BlockList, but of course that breaks the new drag and drop functionality. It's not clear to me why commenting that out is fixing the issue, but hopefully it can help point us in the right direction for a proper fix.

#39089 is the PR that added the CellRendererComponent, cc: @geriux and @fluiddot

[fluiddot]

I can "fix" this issue by commenting out the CellRendererComponent prop within our BlockList, but of course that breaks the new drag and drop functionality. It's not clear to me why commenting that out is fixing the issue, but hopefully it can help point us in the right direction for a proper fix.

#39089 is the PR that added the CellRendererComponent, cc: @geriux and @fluiddot

@mchowning, good catch! @geriux already addressed the issue with the CellRendererComponent in this PR 🎊 . Looks like this issue and wordpress-mobile/gutenberg-mobile#4864 are both related to the onLayout handler on that component, so that fix will most likely solve both at the same time.

[geriux]

I can confirm that #41105 fixes the issue so I'll close this since it was already merged 👍