I currently get the error "Invalid JWT token. Could not resolve issuer token" (401 error) when trying to start a new SP2013 Workflow instance.
I deleted the WF farm already and recreated it (and re-registered with SP). I can create and publish workflows with SharePoint designer. When starting a new instance it starts, but then fails. In Fiddler I can see a lot of 401 errors with said error message. When browsing to localhost:12291 I get a 403 - when executing the browser as Administrator, I can access the XML served by the workflow service. User Profile Service is running, and synching with no problems. I ran multiple full synchs already.
I can't find any error message in the event log, none in the ULS log. The debug table just states the obvious: "Attempt 2 of the HTTP request to 'http://sp.dev/sites/test/_vti_bin/client.svc/web/lists/getbyid(guid'2f523828-6687-43f1-a5b7-af144fea8739')' will be made in 00:00:06." - all 401 errors.
How do I reset my system? how do I do further testing?