With a new install, clicking AMR button generates lua error in line 792. Fix is to check for existence of data.LastTalentConfig before attempting to access spec attribute.
Looking at the code, the only way I could see that particular error happening is if your character currently does not have a specialization… which I believe is only possible during the intro with a new character before it unlocks the ability to choose a specialization.
In general… the addon and website won’t behave well until you actually have a specialization chosen.