Error when running test suites with coverage reports

I've built Opaque on a fresh install of Ubuntu 18.04 following the documentation. I can successfully run build/sbt test (all tests pass), but build/sbt clean coverage test gives the following error:

org.apache.spark.SparkException: Job aborted due to stage failure: Task 2 in stage 0.0 failed 4 times, most recent failure: Lost task 2.3 in stage 0.0 (TID 5) (ryan-dev.internal.cloudapp.net executor 0): java.lang.NoClassDefFoundError: Could not initialize class edu.berkeley.cs.rise.opaque.RA

(A number of suites receive the same error)

[info] Run completed in 6 minutes, 43 seconds.
[info] Total number of tests run: 161
[info] Suites: completed 11, aborted 10
[info] Tests: succeeded 161, failed 0, canceled 0, ignored 10, pending 0
[info] *** 10 SUITES ABORTED ***
[error] Error during tests:
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionOpaqueUDFSuite
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionJoinSuite
[error]         edu.berkeley.cs.rise.opaque.tpch.MultiplePartitionTPCHSuite
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionSubquerySuite
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionSortSuite
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionUnionSuite
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionLimitSuite
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionFilterSuite
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionAggregationSuite
[error]         edu.berkeley.cs.rise.opaque.MultiplePartitionCreateSuite
[error] (test:test) sbt.TestsFailedException: Tests unsuccessful

Reproduce the failure with build/sbt clean coverage test after confirming that build/sbt test passes on Ubuntu 18.04. Start with the NoClassDefFoundError for edu.berkeley.cs.rise.opaque.RA and compare the aborted suites with the successful run; done means coverage tests complete without aborting and the listed suites pass.