How do I save files to my appData folder in Windows WebView2 Exports?

When I export my c2 build as webview2 and try to export a file from my app/game to \AppData\Roaming\myApp I see the message:

'app.localhost cant open files in this folder because it contains system files.'

Is there a way to bypass this? I am reading about setting picker tags to "<roaming-app-data>" but that doesnt seem to have any effect at all...but I could be using it wrong.

P.S Nw.js exports seem to allow saving to appData, but I cant use it because because nw.js is huge (100Mb+).

Cheers