Upgrade v2.1 service mknotifyd stopped and TLS

hi, after upgrading to version 2.1 on an infrastructure consisting of one master and two slaves, I found that the mknotifyd service on the master has stopped (state ‘stopped’).
From the provided configurations, I cannot understand why I see local connections (localhost) in the mknotifyd.state file on the slaves. Can you help me understand the problem?

Master
→ Asynchronous local delivery by notification spooler
→ Connect to remote sites 192.168.191.6 (slave01) , 192.168.191.7 (slave02)
→ Use unverified TLS encryption, fall back to plain text

Slave01, Slave02
→ forward to remote site by notification spooler
→ Accept incoming TCP connections 6555
→ Encrypt communication with TLS
→ No authentication

-------------------- Master log mknotifyd.state --------------------
Site:                     cmkdc_slave01 (192.168.191.6:6555)
Connection:               192.168.191.6:6555
Type:                     outgoing
State:                    established
Status Message:           Successfully connected to 192.168.191.6 at port 6555
Since:                    1690378894 (2023-07-26 15:41:34, 88 sec ago)
Connect Time:             0.004 sec
Notifications Sent:       0
Notifications Received:   4
Pending Acknowledgements: -
Socket FD:                4
Encryption:               upgradable
HB. Interval:             10 sec
HB. Timeout:              3 sec
LastIncomingData:         1690378982 (2023-07-26 15:43:02, 0 sec ago)
LastHeartbeat:            1690378974 (2023-07-26 15:42:54, 8 sec ago)
InputBuffer:              0 Bytes
OutputBuffer:             65 Bytes

Site:                     cmkdc_slave02 (192.168.191.7:6555)
Connection:               192.168.191.7:6555
Type:                     outgoing
State:                    established
Status Message:           Successfully connected to 192.168.191.7 at port 6555
Since:                    1690378894 (2023-07-26 15:41:34, 88 sec ago)
Connect Time:             0.005 sec
Notifications Sent:       0
Notifications Received:   1
Pending Acknowledgements: -
Socket FD:                5
Encryption:               upgradable
HB. Interval:             10 sec
HB. Timeout:              3 sec
LastIncomingData:         1690378974 (2023-07-26 15:42:54, 8 sec ago)
LastHeartbeat:            1690378974 (2023-07-26 15:42:54, 8 sec ago)
InputBuffer:              0 Bytes
OutputBuffer:             0 Bytes

--------------------  Slave01, Slave02 log mknotifyd.state --------------------
# mknotifyd - current state
Version:         2.1.0p30
Updated:         1690381416 (2023-07-26 16:23:36)
Started:         1690364829 (2023-07-26 11:47:09, 16587 sec ago)
Configuration:   1690378877 (2023-07-26 15:41:17, 2539 sec ago)
Listening FD:    4
Encryption:      encrypted

Spool:           New
Count:           0
Oldest:          -
Youngest:        -

Spool:           Deferred
Count:           0
Oldest:          -
Youngest:        -

Spool:           Corrupted
Count:           1
Oldest:          1690364689 (2023-07-26 11:44:49, 16726 sec ago)
Youngest:        1690364689 (2023-07-26 11:44:49, 16726 sec ago)

Site:                     cmkdc
Connection:               127.0.0.1:6555
Type:                     incoming
State:                    established
Since:                    1690378897 (2023-07-26 15:41:37, 2519 sec ago)
Notifications Sent:       5258
Notifications Received:   0
Pending Acknowledgements: -
Socket FD:                5
HB. Interval:             10 sec
LastIncomingData:         1690381407 (2023-07-26 16:23:27, 9 sec ago)
LastHeartbeat:            1690381415 (2023-07-26 16:23:35, 1 sec ago)
InputBuffer:              0 Bytes
OutputBuffer:             0 Bytes

Hi,

that looks similar to this problem :