Never had this issue before with the app but am travelling DFW-JFK-LHR all on one ticket having Virgin Silver (shows as Silver Medallion in the app/Skyteam Elite) and usually I always get 2 bags for free (this happened correctly on my outbound journey even in Comfort Plus) and this is my return journey. The app is wanting to charge me $100 when I put in the number of bags so just wondered if this is some new bug that has developed? The only thing I can think of is the JFK-LHR is on VS and everything was purchased through VS so the boarding pass displayed lists the VS flight numbers on each pass and not the DL ones.

I relooked at the rules on the website and even tried the bag fee checker thing and can't figure it out why I'm being charged: