Teams REFER - SBC sending duplicate INVITEs after INVITE is rejected

Hello,

I observe following:
1 Incoming call from provider, sent to Teams, Teams user responds.
2 REFER send to SBC by Teams.
3 The first INVITE following the REFER, after 180 RINGING, it receives a 480 Temp. Unavailable. —> transfer destination is not answering.
4 Then, SBC sends two INVITEs to Teams, which receive a 500 Internal Server Error (reason: transfer call without draft call data)
5 After that, two more INVITEs are send to the provider by the SBC, which receive 487 Request Terminated.
6 Finally, the SBC sends a NOTIFY to Teams (terminated;reason=noresource), and then a BYE to the provider and Teams.

I don't understand why the SBCs sends those INVITEs after the first one is rejected, and according to Microsoft it shouldn't do that: