During rolling upgrade, data are correctly migrated from source cluster to target cluster, however, after disconnecting the last source node, all migrated data disappears from target cluster (i.e. all source data are lost). This happens randomly. Can be reproduced with HotRodRollingUpgradesDistIT (version form JDG PR #1187) in about 30-50% of test runs. This happens only in case of clusters, I've been never able to reproduce this issue with only on source and once target node.