The problem is based on the fact that MMM-Wunderlist currently uses the official (but deprecated) wunderlist-module to access the API. Looking around and finding no suitable replacement for Wunderlist, I created a fix for this, which seems to run stable (at least for the last two days). (I also recently created a PR which allows the use of multiple accounts and multiple instance with MMM-Wunderlist …)
If you would appreciate a fix, give this post an upvote (As a PR still means work…)
@schwoediauer You are right, the situation about wunderlist is quite diffuse. According to them, wunderlist will be discontinued in the long run :crying_face: (talking years?). However, the IOs App has been updated quite recently (30th March 2018), so they still seem to keep it alive (?). For me Microsoft ToDo can not replace the to-the-pointness of wunderlist…