Upgrade 11.0.3 -> 12 failed in post rebuild: Invalid favorite_link

Hi, 

currently upgrading an instance from 11.0.3 to 12. On 11.0.3 with PHP: 7.4.3 and Mysql: 5.7.38. Everything seems to work correctly. When we start the upgrade with the silent installer (or ui installer doesn't matter much) we eventually hit the following error: 

Tue, 14 Jun 2022 07:08:46 +0000 [Upgrader] - Verifying audit tables for modules: Leads,Cases,Bugs,ProjectTask,Campaigns,Prospects,Contacts,Accounts,Opportunities,Notes,Calls,Meetings,Tasks,EmailAddresses,Contracts,ProductTemplates,Quotes,Products,RevenueLineItems,ForecastManagerWorksheets,Quotas,BusinessCenters,Shifts,ShiftExceptions,Messages,Purchases,PurchasedLineItems,DataPrivacy,ReportSchedules,Tags,KBContents,KBContentTemplates,Escalations,DocumentTemplates,DocumentMerges,aconf_Configurator,aconf_Import_Match,aconf_Import_Auto_Fill
Tue, 14 Jun 2022 07:08:46 +0000 [Upgrader] - Database repaired
Tue, 14 Jun 2022 07:08:46 +0000 [Upgrader] - Start rebuilding relationships
Tue, 14 Jun 2022 07:09:33 +0000 [Upgrader] - ERROR: Exception: Invalid link favorite_link
Tue, 14 Jun 2022 07:09:33 +0000 [Upgrader] - Finished script 2_Rebuild
Tue, 14 Jun 2022 07:09:33 +0000 [Upgrader] - ERROR: Post-upgrade stage failed! Error executing post scripts

We already tried the following but without any luch: 

- truncate the relationships table in the database (it's not used anymore to my knowledge)

- prior upgrade hit the repair relationships and do a quick repair / rebuild. 

Does anyone else have any idea what the cause could be and most importantly a solution.