I wrote a code to catch the email replies into case feeditem object. below is my code and its working fine for all the attachments but failing for few PDF files. could anyone please if am Missing anything here.

Trigger : 

trigger emailToPostChatter on EmailMessage (After insert) {
    
    Set<Id> EmailId = new Set<Id>();
    for (EmailMessage email : trigger.new) {
        
        if(email.FromAddress !='ssp-support-test@sureify.com'){
            List<User> u = [select Id, Name, Email from user where Email =: email.FromAddress AND isActive = true];
            FeedItem post = new FeedItem();
            post.ParentId = email.ParentId;
            
            post.Visibility = 'AllUsers';
            post.createdById = u[0].Id;
            post.Title = 'EmailMessageFeed';   
            string emailBody = email.TextBody;
            
            
            
            post.Body = '\n' + emailBody;
       
            insert post;
            
            if(email.HasAttachment){
                system.debug('EmailMessage Id inside If = '+ email.Id);
                emailToPostChatterHelper.InsertFeedAttachment(email.Id, Post.Id, u[0].Id, email.ParentId);
                
            }
            else{
                emailToPostTochatterAlerts.fireExternalEmail(email.ParentId, post.Id);
                emailToPostTochatterAlerts.fireInternalEmail(email.ParentId, post.Id);
            }

        } 
    }
}

===== > Helper class to handle attachments

public class emailToPostChatterHelper {
    @future
    Public static void InsertFeedAttachment(Id emailId, Id postId, Id userId, Id CaseId){
              List<ContentDocumentLink> contDocLinks = [select Id, LinkedEntityId, ContentDocumentId from ContentDocumentLink where LinkedEntityId =: emailId];
              List<ContentDocument> cntdList = new List<ContentDocument>();
              List<ContentVersion> cntvList = new List<ContentVersion>();
              List<FeedAttachment> FeedAtchlist = new List<FeedAttachment>();
              set<Id> FeedId = new set<Id>();
  
            if(contDocLinks.size()!=null){
            for(ContentDocumentLink contD : contDocLinks){
                ContentVersion contvrsn = [select Id from ContentVersion where ContentDocumentId =:contD.ContentDocumentId];
                
                ContentDocument cntd = new ContentDocument();
                cntd.Id = contD.ContentDocumentId;
                cntd.OwnerId = userId;
                cntdList.add(cntd);
               
                
                FeedAttachment feedAttachment = new FeedAttachment();
                feedAttachment.FeedEntityId = postId;                          //Id of FeedItem
                
                feedAttachment.RecordId = contvrsn.Id;
                system.debug('emailToPostChatterHelper feedAttachment.RecordId ='+feedAttachment.RecordId);
              
                  feedAttachment.Type = 'Content'; 
                  
                 FeedAtchlist.add(feedAttachment);
                
                }
                
              
                insert FeedAtchlist;
                update cntdList;
          
            }
         
    }

}