Dan,
Dan, thanks for your reply, I have just changed the ARR into LHR and just selected the Approach and STAR without a Transition this time and it has solved the issue.
Along with the flashing there were no Step Climb Markers or Fix Page predicted ETA-ALT markers either. I presume the issue is something with the coding in the FMC, or perhaps the Navigraph Nav Data that it doesn't like and therefore cannot compute times/distance/fuel?
Regarding the name, I knew I'd forgotten something! Apologies!
Regards
Oliver Barker