File Sharing between licensed account holders

Yes. The issue is usually one of two things:

 1. Email sharing notifications being quarantined
Check Microsoft Defender > Email & collaboration > Policies & rules > Threat policies > Anti-malware.
Look at the Common Attachment Types Filter. If legitimate file types such as .docx, .xlsx, .pdf, or .zip have been added, remove them.

 2. Actual shared files being quarantined in SharePoint/OneDrive/Teams
Check Quarantine > Files and look at the Detected by field:

• AV = antivirus/signature detection
• MDO = Safe Attachments for SharePoint/OneDrive/Teams

For confirmed false positives, submit the file as clean, then add the file hash to the Tenant Allow/Block List, and release the file. Avoid broad exclusions.

Also check the audit log for recent security policy changes, such as enabling Standard or Strict preset security policies.

This is the correct, safe diagnostic path.

My answers are voluntary and without guarantee!

Hope this will help you.