Kafka Streams Topology stuck in num.stream.threads=50 and 100 partitions - apache-kafka

Question

There is a topology:
kStreamBuilder.stream(kafkaProperties.getInboundTopicName(), consumed)
.filterNot((k,v) -> Objects.isNull(v))
.transform(() -> new CustomTransformer(...))
.transform(() -> new AnotherTransformer(...))
.to(kafkaProperties.getOutTopicName(), resultProduced);
with configured
num.stream.threads: 50
On startup application stuck with constantly logging messages(I'm not 100% sure it stuck but after 20 minutes there are no changes in the state and CPU, network usage is very high) :
State transition from RUNNING to PARTITIONS_REVOKED
AbstractCoordinator : [Consumer clientId=consumer_id-StreamThread-1-consumer, groupId=group_id] (Re-)joining group
AbstractCoordinator : [Consumer clientId=consumer_id-StreamThread-2-consumer, groupId=group_id] (Re-)joining group
AbstractCoordinator : [Consumer clientId=consumer_id-StreamThread-3-consumer, groupId=group_id] (Re-)joining group
AbstractCoordinator : [Consumer clientId=consumer_id-StreamThread-4-consumer, groupId=group_id] (Re-)joining group
AbstractCoordinator : [Consumer clientId=consumer_id-StreamThread-5-consumer, groupId=group_id] (Re-)joining group
etc.
Topic has 100 partitions.
What we noticed: every transformer uses it's own persistentStateStore. After replacing it to inMemoryStateStore there still were logs written above but after ~3 minutes topology started successfully.
Kafka streams version 2.1.0.
Broker version 1.1.0