Sitemaps no longer accessible

I start Webscraper extension on 3/01/2018 and it no longer works. I can see the sitemaps but when I open them there are no selectors anymore. Clicking the sitemap menu does nothing. Making a new sitemap is possible but I cannot add any selectors. Last time I used it was on 19/12/2017 and it was working fine.

Webscraper 3.3.3
Chrome: 49.0.2623.112
Vista 64bit
No errors in console tab

Please resubmit this as a bug report including error messages from the background page and os, chrome version.