In Xamarin Android - How to regenerate the Resource.designer.cs
I tried to mark all the XML file\'s Build Action as \"AndroidResource\" and still the Resource.designer.c
The Resource.designer.cs folder would update as @Brendan Zagaeski mentioned.
However, since it seems like that didn't solve your problem it looks like Xamarin didn't recognize any of the changes you made. At least this is what happened to me.
I ended up solving it by renaming the generated "Layout" folder to "layout" ( I did the same for drawable and values). After that, just by building the project again the Resource.Designer updated successfully.
Hope this helps someone.