1. Maybe HR read the candidate's resume and found that it didn't match the position well, so he didn't plan to invite the candidate for an interview.
2.HR read the candidate's resume and found it appropriate, but the HR department found it inappropriate, so it didn't invite the candidate for an interview.
3.HR forgot to give feedback to the candidate. Regardless of whether the candidate is suitable for this position, HR should give feedback to the candidate after reading the resume, but HR handles too many resumes every day, so there will be cases where feedback is forgotten.