Since March many people are still RBVO, so I wouldn't play that point if I were you
Of course they need to be informed of any change in employment circumstances, so if you are having no acknowledgement by online form, try email. If you get no joy after the email I would just leave it. It should be easy to prove you have informed them, and the only real relevance of a change in employment is if they do employment verification since they will attempt to contact you at your place of employment at the same time they attempt to contact your employer.
Wayne.