Activity filter hides discussions from diffs

Summary

Manipulating the activity filter can cause inline discussions to be hidden from the diffs and not return without a page refresh.

Steps to reproduce

Navigate to an MR with inline discussions, such as gitlab-com/www-gitlab-com!17928 (merged)

Set the activity filter to "Show History Only". Select the Changes tab, then select the Discussion tab, then set the activity filter to "Show All Activity." Then select the Changes tab again. Observe that inline discussions are no longer visible.

What is the current bug behavior?

Inline discussions are not visible.

What is the expected correct behavior?

After setting the activity back to "Show All Activity", inline discussions should become visible in the diffs again.

Output of checks

This bug happens on gitlab.com.