Solved: First Win 2016 DC in Win 2008 R2 Domain complains that Migration to DFSR has not reached a consistent state

We have a Domain with 10 Win 2008 R2 Domain Controllers in different sites. More than a year ago we migrated from FRS to DFRS successfully. Now I brought the first Win 2016 Domain Controller into the Domain (let's name it WIN2016DCNAME here). Generally the promotion worked well (incl. Forest and Domain Prep), although the server crashed once after the reboot following the promotion to a DC. Since then all looks good and the system is stable incl. SYSVOL Replication. "repadmin /replsummary" also shows all now 11 DCs in sync.
By chance I came across an indication that there is an issue with DFSR and found that "dfsrmig /getMigrationState" shows the following status:

The following domain controllers have not reached Global state ('Eliminated'):

Domain Controller (Local Migration State) - DC Type
===================================================

WIN2016DCNAME ('Start') - Writable DC

Migration has not yet reached a consistent state on all domain controllers.
State information might be stale due to Active Directory Domain Services latency.

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Further DCDIAG shows the following errors:

      Starting test: Services
            Invalid service startup type: NtFrs on WIN2016DCNAME, current value DISABLED, expected value AUTO_START
            NtFrs Service is stopped on [WIN2016DCNAME ]
         ......................... WIN2016DCNAME failed test Services
      Starting test: SystemLog
         ......................... WIN2016DCNAME passed test SystemLog
      Starting test: VerifyReferences
         Some objects relating to the DC WIN2016DCNAME have problems:
            [1] Problem: Missing Expected Value
             Base Object: CN=WIN2016DCNAME,OU=Domain Controllers,DC=XXX,DC=com
             Base Object Description: "DC Account Object"
             Value Object Attribute Name: frsComputerReferenceBL
             Value Object Description: "SYSVOL FRS Member Object"
             Recommended Action: See Knowledge Base Article: Q312862

         ......................... WIN2016DCNAME failed test VerifyReferences

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And finally I find the following error in C:\Windows\debug\DfsrMig_xxx.log

20181009 10:04:13.971 5148 MIGM   738 [ERROR] main Error:
+	[Error:9512(0x2528) Process main.cpp:602 5148 C Migration have not yet reached to a consistent state on all Domain Controllers]
+	[Error:9512(0x2528) ProcessGetMigrationState main.cpp:485 5148 C [b]Migration have not yet reached to a consistent state on all Domain Controllers[/b]]

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It seems that the new DC is still waiting for the Migration to DFSR, although it already uses DFSR and replicates the SYSVOL. As FRS is not supported on Win 2016 I can understand, that the new DC cannot complete the FRS to DFSR migration. But I cannot believe that this status should be normal for that situation as it should be common to add Win 2016 DCs to a Win 2008 R2 Domain. The quoted Knowledge Base Article Q312862 is for Win 2003 so it does not really apply.

Because of the error in DCDIAG that NtFrs is disabled I enabled and started the Service but it immediately stops and writes into C:\Windows\debug\NtFrs_xxxx.log the following, which seems that FRS is aware that the Migration is complete, as Status 3 is ELIMINATED state:

<DbgInitLogTraceFile:           6860:  1884: S0: 08:28:28> :S: Full pathname for c:\windows\system32\ntfrs.exe
<Migrate:                       6860:  1376: S0: 08:28:28> Returning DFSR Migration Local state: 3.
<FrsPrintEvent:                 6860:   619: S0: 08:28:28> :E: Eventlog written for EVENT_FRS_STOPPED_ELIMINATED_STATE (13575) severity: Error  at: Wed, Oct 10 2018  08:28:28

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It did not change the situation.

May this situation be a result of the crash during the first boot after promotion?
Can it be safely ignored?
Would you recommend to demote the DC and then promote it again? I would like to avoid to reinstall the OS and to give it a new name!
Any other suggestions?