This is about the one-place predicate “ignorant”, not about the two-place predicate “ignorant of”. My impression as a non-native speaker is that a negative connotation attaches to the first, but not the second. There might also be a two-place version of “ignorant” with a negative connotation: “ignorant about”.
I am not a native speaker, so I looked up, what google says about ignorant:
adjective: ignorant
lacking knowledge or awareness in general; uneducated or unsophisticated.
(informal) discourteous or rude.
The connotation is negative. The neutral word would probably be “uninformed”.
This is about the one-place predicate “ignorant”, not about the two-place predicate “ignorant of”. My impression as a non-native speaker is that a negative connotation attaches to the first, but not the second. There might also be a two-place version of “ignorant” with a negative connotation: “ignorant about”.