Thanks, it makes sense what you say JCD. The way it's all structured leaves a lot of room for confusion, both of the user and of the system itself.
What I have now seen, if I create a new profile from scratch (as opposed to saving my current settings as a new profile) and I then change the settings of this new profile then everything works fine again. I can then update the new profile without issues. The problem seems to arise, without fail, if I create a new profile using current settings.