Flashing Issues when 500kbps Bus Exists in System

We have been seeing issues when sending projects to IQAN modules when a mix of 250kbps and 500kbps baud rates exist on the same module.  

In our case, we have a multi-master system with (2) MC43 modules.  The diagnostic bus on CAN-A for both at 250kbps.  The modules are addressed as 0 and 1.  The 0 address module has all CAN bus speeds set at 250kbps.  The 1 address module has all CAN bus speeds at 250kbps, with the exception of CAN-C as 500kbps.  CAN-C is connected to a truck engine bus that continues to communicate during the flashing process (data is always present on CAN-C whenever the MC43 is powered on).  

When we attempt to send a project, the flashing process stalls once the module with a 500kbps bus is updated.  This happens very regularly, and happens with IQAN Design 4, IQAN Run 4, IQAN Design 6, and IQAN Run 6.  The process seems to get to the point where the 500kbps module is updated, but can't proceed to any additional modules in the system or finalize the process.  This is very troublesome when remote flashing system updates via IQAN Go.  Disconnecting the 500kbps bus prior to flashing does allow us to avoid this issue, but this step is often forgotten about by our service techs.

Is there a reason that the system stalls/errors out when flashing master modules with a mix of baud rates?