Your employer is not permitted to deposit the whole $10,000 bonus as an elective deferral. The employer must follow your election, either as a one-time deferral that you explicitly requested (which you apparently did not request) or as the percentage of your pay that you had elected.
Was this instead an employer profit-sharing contribution and not an elective deferral from your compensation (i.e., not supplemental wages)? The $27,000 limit is only for your elective deferrals (combined between your two employers). Employer contributions are subject to per-plan limits which your employer is required to enforce. Matching contributions are also employer contributions. Although matching contributions are related to your elective deferrals, they are not elective deferrals are not a factor in determining whether or not you have exceeded the $27,000 elective-deferral limit.
