Hi aspirant,

No it will not affect your neet results by any means. It is not compulsory to enter the 11th standard marks as there is no official examinations conducted by board's for it.  You do not have to upload class 11th marksheet but you need to enter the details of class 11th such as passing year, pass status, Place of Schooling, Qualifying Examination, Type of School College, Qualifying Examination State, Qualifying Examination District, School Board etc.

Hope it helps!!