Word that means "to be oblivious to" but not on purpose?

I searched for be oblivious to in Thesaurus but it only has synonyms of ignore (to disregard intentionally). I'm looking for something more silimiar to "to not to know".

Example sentence:

Truth be told, he __ the answer himself.

Answer

How about overlook or miss?

M-W:

overlook: to look past : miss

miss: to fail to comprehend, sense, or experience

Your example:

Truth be told, he overlooked the answer himself.

Truth be told, he missed the answer himself.

In both of these examples, he simply didn't see or notice the answer. No intentionality involved.

Note: @Irhala mentions miss in a comment.