I cannot reproduce. Please attach a small sample survey. Thank you.

File limesurvey_survey_196786.lss is attached to this ticket.

The problem is that the ranking question has an invalid question code. Purely numerical question codes should not be valid anymore. This seems to be a validation problem in the GUI. Assigning to the right person :-)

Hm, there seem to be more issues:

If I define min and max neede answers, these numbers are not used for the evaluation whether I completed the question. There is always the error message as mentioned in my description of this ticket. And the red remark/error message in the question is misleading. It states that ALL options have to be ranked, even if I restrict to a max number which is less than the max number of options.

I will upload an example, see code "sieben".

That's a known behaviour. Making the question mandatory automatically means that all items must be ranked. if you want only a " rank x out of Y" scenario just use the particular question attributes. (it is also mentioned in the documentation).