Spark scope mode is broken

Hi,
 
we have an issue with our current deployment of zeppelin on k8s, and more precisely with spark interpreter.
 
For reference - the spark context is: scala 2.12.10 / spark 2.4.7
 
We have a weird behaviour, running the spark interpreter in per note, scoped
 
To reproduce currently - we restart the spark interpreter in scoped per note, and create two notebooks (A & B) with the same following code: 
 

%spark
import spark.implicits._

List(1, 2, 3).toDS.map(_ + 1).show

 
1- we run notebook A successfully
2 - we run notebook B  - it fails with class cast exception
 

org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 24.0 failed 4 times, most recent failure: Lost task 0.3 in stage 24.0 (TID 161, 10.11.18.133, executor 2): java.lang.ClassCastException: cannot assign instance of java.lang.invoke.SerializedLambda to field org.apache.spark.rdd.MapPartitionsRDD.f of type scala.Function3 in instance of org.apache.spark.rdd.MapPartitionsRDD at java.io.ObjectStreamClass$FieldReflector.setObjFieldValues(ObjectStreamClass.java:2287) at java.io.ObjectStreamClass.setObjFieldValues(ObjectStreamClass.java:1417) at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2293)

 
Anyone having a working zeppelin deployment with k8s / spark 2.4 - scala 2.12 ?