Issue with october v4

[c2webstudio]

1. Updated october from v3.7 -> v4
2. Go to sitemap settings and edit/create a record and save
3. Sitemap breaks with errors

Error shown in settings
Unable to find the sitemap.

Data object stored in database
{"\u0000*\u0000items":[],"\u0000*\u0000escapeWhenCastingToString":false}