Fixed it myself, after reading this post:
I installed the last stable version (3886) and now everything works fine again. So this seems to be a (severe) problem of build 3890. Please fix this!
When I publish or preview a file that has been working fine for a long time, none of the interactions are working. The hotspots aren’t visible either. Same problem in Safari, Chrome or Firefox. But when I publish the file to Axure Cloud, all is fine. How can I solve this problem, that makes working with Axure near impossible? I am working on a rather complex project, so there are lots of interactions, dynamic panels and different states.