Reply button of received forum post doesn't work after using scroll button

Steps to reproduce:

Create a forum with a screenful of posts, shared between devices A and B
Write a new top-level post on device A
When the post is received on device B, use the scroll button to show it
Try to reply to the post on device B - the reply button doesn't work

If I scroll to the post manually rather than using the scroll button, the reply button works. The reply button works on device A (where the post was written). It can be made to work on device B by touching the reply button on another post, backing out, then touching the reply button on the new post.