Hi,
obviously you set the question to "mandatory".
Unfortunately you neither provided a lss export of these relevant questions (which is always the best to show us the entire settings) nor showed at least your settings here
Therefore I should say:
1. option: Set the question to "not mandatory". Your desired number of ranked items you get by setting "Minimum answers" and "Maximum answers"
2. option: Set the question to "mandatory" and set the "maximum columns for answers" to your desired maximum.
I should prefer option 1. In case you try to procced without ranking any item you see in option 2 the misleading hint "Rank all items" (though here "all" refers to 3, but the participant will not know)
Now a word to your version.
Your version didn't get any updates, security fixes for nearly 4 years. It was released October 23, 2019.
Regarding GDPR it is irresponsible to use such an old version.
Joffm