you have a blog post about how to edit the datastandard XAML files using visual studio.
did something change in 2018? I get a "object reference" error when following those steps.
do you get any details in your error list? You can open it with Ctrl + W, E if it is not visible. Also what was your exact workflow? I don't get that error on my system
are you referencing the Datastandard 2018 libraries or did you link to some older versions accidentally? This could cause a null pointer exception if the 2018 dialogue references stuff that is not available in the older libraries. (not tested, but could be)
Could you also send me your dialogue so I can try it on my system?