I have a approval in process to post the attachments to Chatter, 

If a record is Approved which is created through UI with attachments, I am able to view the preview of Attachments.

I am not able to see the preview of attachments after approval of records  created through inbound email.

Is any thing i need to add in the code or?

public class EmailParsingActivity {
    
    public void attachToRecord(Messaging.InboundEmail.BinaryAttachment[] bAttachments, ID abcdRecId) {     
        String contents='';                       //ok
        List<Attachment> listAttach = new List<Attachment>();

        if(bAttachments != null) {
            for(Messaging.InboundEmail.BinaryAttachment bAttach : bAttachments){  //ok
                system.debug('attach file name ' + bAttach.filename);
                
                Attachment attach = new Attachment();
                
                //attach.Body = Blob.valueOf(bAttach.body.toString());
                String b64Data = EncodingUtil.base64Encode(bAttach.body);
                //Blob bab = bAttach.body;
                attach.Body = Blob.valueOf(b64Data);
                attach.Name = bAttach.filename;    // name of the attachement should be same a attached to email
                //attach.parentId = submitRecord.Id;
                attach.parentId = abcdRecId;
                listAttach.add(attach);        
            }
            system.debug('attach list size ' + listAttach.size());
            insert listAttach;
        }
    }
    
}

I would appreciate if someone assist me with the solution. Thanks in Advance-----