Background color for Change Logs (Multi-select Text fields)

I tried to utilize the following formula to change the background color of my multi-select text field in the event that the new value changes from the old value: 

If([Value - Old]<>[Value - New], "<div style=\"background-color:#ABD4CD;\" >"&[Value - New]&"</div>",[Value - New])

I used THIS video to create a change log, but I am unable to use the formula above to change the background color of newly modified multi-select text fields. Does anyone have a workaround for this?

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