Teams/Groups/Sharepoint migration completed with issues. Owners account is not matched or migrated. (4245802)

Migrating Teams, O365 Groups or SharePoint is completed but states "migrated with issues". Looking at the logs it shows the Owners group is not able to be matched or migrated, which ODM reference as "<name> Owners account is not matched or migrated". There's no such account called "<name> Owners" and it's not shown in Accounts in ODM.

ODM is incorrectly reporting that <name> Owners account is not matched or migrated, which is the cause of partial migration failure. 

In fact the "<name> Owners" is not an account but rather a SharePoint group entity. All this group's members should be matched or migrated by ODM through Accounts in order for warning "completed with issues" to go away.

In order to reach the list for Teams or MS365 Groups, access Admin Center of the source tenant, Teams and Groups, click on the Team/Group name to bring out properties window. Write down the name of linked SharePoint site or simply click on the link.

It should open SharePoint site. Click on the cogwheel in top right corner and click on Site Permissions. Expand site's Owners group and write down names of all owners. Make sure that all site owners are matched or migrated by ODM in Accounts section.

Once it's done, migrate a Team/Group/SharePoint site again.

This warning can also occur if the default SharePoint Groups were replaced in the source site, you can check this by going to the SharePoint Site Settings > Site Permissions, you may see 2 Owners, Members and Viewers group, for example: "<nameA> Owners" and also "<nameB> Owners", in this case the warning can be ignored as duplicate default groups will not be migrated but the users will be added to the single default group in the target (<name> Owners).