File diffs link under the Changes tab no longer displaying after upgrading to Bamboo 4

With previous versions of Bamboo, the "(diffs)" link was available when viewing the Changes tab per build.

However, after upgrading to Bamboo 4.0, that ability seems to have disappeared, despite having the same Actions -> Configure Plan -> Source Repositories -> Plan Repository -> Advanced Options -> Web Repository/URL/module correctly specified. (The absence of the link is highlighted by the red arrow in the attached screenshot.)