Cannot receive UDP in docker container

Coming from https://stackoverflow.com/questions/63328454/howto-test-if-container-receives-udp:

I'm having troubles with my container receiving UDP responses. I've tried to test this and the test already fails (using OSX):

~/htdocs/evcc master 17s
❯ docker run -p 7090:7090/udp -it --rm alpine
/ # nc -u -l 0.0.0.0 7090

and from the host:

~/htdocs/evcc master
❯ nc -u 0.0.0.0 7090                         
ljkhgdkfjhg

Yet, no echo inside the container. The same works fine when both are run on the host. Same also works when e.g. using Ubuntu as image.