Unexpected error when clicking on "View latest Clover information"

The following message is found in the logs:
2014-03-07 16:17:42,919 WARN [http-bio-8085-exec-9] [BuildResultsSummaryAwareInteceptor] Action com.atlassian.bamboo.build.coverage.ViewCloverBuildResults@177d9b95' is buildResultsSummaryAware but no build can be found

Also, prior to this, when clicking on the Clover tab (which is next to Tests), the following trace is written to the logs:

2014-03-07 16:17:42,919 WARN [http-bio-8085-exec-9] [BuildResultsSummaryAwareInteceptor] Action com.atlassian.bamboo.build.coverage.ViewCloverBuildResults@177d9b95' is buildResultsSummaryAware but no build can be found

2014-03-07 16:12:44,817 ERROR [http-bio-8085-exec-12] [runtime] Expression immutableBuild is undefined on line 7, column 47 in viewCloverSummary.ftl.

Expression immutableBuild is undefined on line 7, column 47 in viewCloverSummary.ftl.
The problematic instruction:
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==> macro header [on line 242, column 1 in freemarker-lib/ui.ftl]
in user-directive ui.header [on line 7, column 1 in viewCloverSummary.ftl]
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Java backtrace for programmers:
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freemarker.core.InvalidReferenceException: Expression immutableBuild is undefined on line 7, column 47 in viewCloverSummary.ftl.
at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:124)