USG Flex 200H - HA "Full Last Sync" failed

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I have a question. Over the weekend, I tried enabling the HA feature on my two FLEX 200 H devices, but it didn't work.
The problem is that the device status is active and the devices are paired, but the "Last Full Sync Status" is failed.
I reset the second device to factory defaults and tried configuring HA three times, but the last full sync always failed.

I used this How to

https://mysupport.zyxel.com/hc/en-us/articles/28563482103698-Zyxel-USG-FLEX-H-Series-HA-Device-High-Availability-Enhancements-HA-PRO

https://support.zyxel.eu/hc/de/articles/24137937783826-Zyxel-USG-FLEX-H-Serie-HA-Einrichtung-der-Hochverf%C3%BCgbarkeit-von-Ger%C3%A4ten-HA-PRO#h_01JJ9QFQABN8BRXYAPZJGT4TCJ

This log comes from the primary device. I no longer have access to the Sendodary.

______________________________________________________

show state vrf main device-ha status
enabled true
initial-role primary
pairing-state paired
pairing-msg Paired
ha-health-state connected
local-state active
local-role primary
active
role primary
sn xxxxxxxxxxxxx
icon-color on
..
passive
role secondary
sn xxxxxxxxxxxxx
icon-color on
..
sync-service-port 49058
flash-log false

______________________________________________________

show state vrf main device-ha summary
summary
last-failover-epoch 0
last-failover-reason ""
last-sync-epoch 1761552343
last-sync-status Fail
failover-count 0
first-failover-epoch 0

Is here someone who can help?