Box E refers to drop down for sales section "long term basis not reported to IRS (noncovered)". Box B is short term noncovered.
Ideally you would enter this as "one by one" with the details, which will put it on Form 8949 and then Schedule D. The other post from 2019 I think means to enter it as a sales summary, which doesn't ask for dates but will trigger the need to mail your 1099-B to the IRS.
Whatever information you are missing you should ideally be able to source from the original statement/confirmation etc. Depends what this sale is for and what information you are missing.
