Query result gives back one additional item with null value

Query result gives back one additional item with null value in case of embedded mode.

cache.size() gives back the correct number however query.execute() gives back one additional item with null value

Cache configuration:

builder.clustering().cacheMode(CacheMode.DIST_SYNC).encoding().key().mediaType("application/x-protostream")
                .encoding().value().mediaType("application/x-protostream").locking().isolationLevel(IsolationLevel.REPEATABLE_READ);
builder.indexing().enable().storage(IndexStorage.FILESYSTEM).path(INDEX_FILE_PATH).addIndexedEntity(XY.class).reader().refreshInterval(1000).
                    persistence().passivation(false).addStore(TableJdbcStoreConfigurationBuilder.class)
                    .dialect(DatabaseType.POSTGRES).shared(true).tableName(TABLENAME).connectionPool()
                    .connectionUrl("jdbc:postgresql://localhost:5432/xxxx").username(USERNAME).password(PASSWORD)
                    .driverClass("org.postgresql.Driver").preload(false).schemaJdbcConfigurationBuilder()
                    .messageName(objectType).packageName(PACKAGENAME).embeddedKey(true);