Help with Microsoft Defender Quarantine - Allowing Secure Emails After Review

Hi everyone, I’m having trouble with Microsoft Defender for Office 365, specifically related to releasing a secure email from quarantine. The email has been identified as safe, but it's still being blocked. Here are the steps I’ve already taken to resolve the issue:

1. Reviewed the Quarantine Section: I accessed the quarantine section in the Microsoft 365 Defender portal and attempted to release the email manually.
2. Added the Sender to the Allow List: I added the sender’s domain and email address to the Safe Senders list in the Anti-Spam policy.
3. Checked the Policies: I verified that the email met all criteria in the Email & Collaboration policies for not being quarantined.
4. Adjusted Filters: I adjusted some filters in the Anti-Phishing policy to be more lenient regarding this specific sender and secure emails.
5. Double-Checked Rules: Ensured that no custom rules or transport rules were set up that might be affecting this sender’s emails.

Despite taking these steps, the email continues to be quarantined, and I'm unsure what else could be causing the issue. Could anyone provide insight into what I might be missing or suggest any additional steps I can take to allow this email to pass through without being blocked in the future?

Thank you so much for your help!