Hi Black Dahlia
Depending on when your PIP was awarded in 2016 - the tribunal panel may or may not have been aware of the change in the law. They are still undertaking the reviews so you may or may not hear from the DWP.
I slightly disagree with the CAB here. On your current review form, the assessor is not going to care that you lost your standard mobility in the past - they are going to assess you on the present, so the most important point is that you prove that you should be awarded standard or enhanced. By all means, mention that your symptoms have been ongoing since 2016 (and earlier), but make sure that you focus on the criteria for the PIP mobility and show how you meet the criteria now.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
