Table 11 of the census concerns pupils on roll with a SEN Provision. If you use the ScholarPack summary you can click on Show Data and the UPN for all students appearing in each category will appear, so you can identify the individuals.
If a student does not appear here under SEN Support, go to their student profile and the Support Tab. If the student has a SEN Provision recorded as No Special Educational Need, even if they receive SEN support in school, they won't feature in the figures for SEN Support.
You may need to end the SEN Provision of No Special Educational Need, and set up a new SEN Provision for SEN Support to have the student appear in the table for code K.