Hi everyone,
today I tried to export a model I built with mecabricks, like I did several times before. I work on win 10 using the latest version of Firefox. My download-folder showed a zip-archive with a file named "scene.mbx". Trying to import it into blender with the import-tool didn't work. When I last exported a model in november, everything was fine. After some ideas what could be wrong, I changed the browser, started the not so popular microsoft edge and export showed the desired .zmbx file.
So for all suffering from the same problem...