LCW to LCWRA advice

Hi hope someone can help.

I have LCW from Jan 2020. I have just reported a new/worsening condition and asked wether I need to provide any fit note and was told no see screenshot below

I have seen on here many times that to be eligible for back pay if LCWRA decision is made, it only applies if fit notes have been submitted continuously.

Where can I find the information that states this please so I can go back to UC and inform them they have advised wrongly

Thanks,

Aaron