@girish Thank you for the pointers!
Reading the comments on "issue 100", I started by blocking my own trackers in Adguard (seemed fun!), which results in Ackee dashboard not opening (haven't found yet how to whitelist it), and Umami dashboard opening, but also still tracking my own visits, even though in Adguard it shows a block of it every time! This was fascinating, but not productive yet...
In the end, yes, it is the browser blocking third party cookies that canceled out the (now) default ignoreOwnVisits in Ackee. I solved that by removing the browser block, using uBlock origin instead, and adding my ackee address to "trusted sites". Seems to be working!
Thank you for the quick response! 🙂