Hi, looking for workaround, knowing that the issue is more related with WebView component, I found this great extension from Profile - lukegackle - Kodular Community, the:
http://thunkableblocks.blogspot.com/2017/06/webviewtools-extension-for-app-inventor.html
using only 2 blocks on the screen init to allow the webview file access give a workaround, thus solve the error access in Fenix 1.5.2.
If moderators consider, change the Thread tittle to something like “Webview error accesing cache dir in Fenix 1.5.2 Release”, maybe is more exact, nothing really related with ChartMakerPlus.
Thanks for your support.