Before you do upload a new ARC file, its always good to remove the old ARC settings first then upload it. Try and let me know.
AN ANNOYANCE BUT HAVE TO DO IT!
Also do take note that the main profile settings like distances and phase settings for the subwoofers will not automatically port over to the other profiles that you activated. ALWAYS remember that after every upload of the ARC settings to the main profile, you will need to go to the settings in the MRX740 like Listener Position to set the distances and go to Bass Management setting to set the Phase values for Subwoofer 1 and 2. I know it is extremely annoying but until Anthem Support do something about it, user will just have to bear with it and make it a routine that for every upload, go through each of the profiles and set those settings to emulate the main profile or else the profile that you have selected for a particular input (source) will sound terrible. The workaround is of course to stick with one profile - i.e. the main profile.