Quick summary

The Calypso dashboard sidebar may overflow beyond the height of the current window. If so, scrolling down the screen should reveal the lower dashboard links. However, very inconsistently, the dashboard content itself does scroll but the sidebar menu does not.

Steps to reproduce

1. Start with a site using the Default interface (enabled at Settings > General).
2. Navigate around Calypso (or to and from Calypso and WP-Admin), particularly to Calypso areas with a lot of sub-links (e.g. Settings, Tools).
3. Scroll up and down the dashboard pages.

What you expected to happen

The sidebar should scroll as needed to reveal any overflow items.

What actually happened

In some cases, the sidebar does not scroll at all, making it impossible to view lower links:

Impact

Some (< 50%)

Available workarounds?

Yes, easy to implement

If the above answer is "Yes...", outline the workaround.

Refreshing the page seems to consistently fix the issue.

Platform (Simple and/or Atomic)

Atomic

Logs or notes

Replicated only on Atomic so far, and only with the default interface. As this is very inconsistent, I'm unsure whether it affects Simple sites or the "classic" interface (and/or WP-Admin).

Initial user report here: 9194220-zd-a8c