No, elective deferrals (including the catch up) are NOT allowed for a regular SEP (if you have an older SAR-SEP, those have different rules). A SEP is limited to the 20% of net earning from self employment (after adjustments, it is less than 20% of your profit).
The "maximize" button seems to be maximizing a 401(k), which does allow elective deferrals (including the catch up).
