HPPLMN search - reason unknown

I was able to perform an test run for the HPPLMN search topic.

See hpplmn search - please consolidate advice.

The capture shows:

nRF9160 SICA B1A
mfw v1.3.3
NB-IoT, PSM: PTAU 24h, Act 4s
SIM-Card: HPPLMN 26201 interval: 2h
Message exchanges every 30min.

PLMN: "26201","D325",9,8,"01CC2B0C"  

(times are times in Wireshark)

1. Exchange
RRC Released 21s, Sleeping 25s => after 4s, no HPPLMN search
 
2. Exchange
RRC Released 1826s, Sleeping 1972s => after 146s, HPPLMN search!

3. Exchange
RRC Released 3626s, Sleeping 3630s => after 4s, no HPPLMN search

4. Exchange
RRC Released 5426s, Sleeping 5430s => after 4s, no HPPLMN search

5. Exchange
RRC Released 7225s, Sleeping 7229s => after 4s, no HPPLMN search

6. Exchange
RRC Released 9026s, Sleeping 9030s => after 4s, no HPPLMN search

7. Exchange
RRC Released 10825s, Sleeping 10964s => after 139s, HPPLMN search!

Please analyze, why the modem starts these HPPLMN searchs.

My understanding is, it is always the PLMN 26201, which is the configured HPPLMN. I don't see the reason, why the searches are executed.

trace-2022-12-16T10-27-46.715Z.zip

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