Image Style Issue Doesn't Work Every Time I posted a previous post about this, but it kind of went a different path, so in the interest of exploring another avenue I wanted to start a new topic to try and troubleshoot this a different way. 

ISSUE: The site runs about 99% perfection, however, there is one issue. One of the image styles doesn't always generate when an image is selected for thumbnail. 

BACKGROUND/EXPERIENCE ON SITE: I have created a website where I am accepting submissions through Webform version 7.x-3.20 on an installation of Drupal 7.32. The reason for it not being updated is due to a specific need to use Hubspot Drupal Integration 7.x.2.0-rc5. Updating breaks the HubSpot integration, so I've come to terms with the issue of security.

SUBMISSION EXPERIENCE: 
 - User fills out form and attaches an image they want to display. 
 - I receive an email to review it as admin for approval. I click the link in the email to travel to the submission within Drupal for approval.
 - I click "select" on the image to generate a thumbnail image and adjust any copy content that may be inappropriate. 
 - I publish the page and review to ensure main image on entry page and thumbnails on overview page have been made correctly. 

PROBLEM: The problem happens in step 3 above. 99% of the time images work without issue and are made into the appropriate thumbnail and entry sizes and crops. However, on occasion the image styles don't work.

WHAT I KNOW:


The uploaded images do make it to the server. I can see the image no issues what so ever before I request it be processed into image styles.
I can recreate the image styles outside of the website and upload them into their specific folders where the images that do work are placed without issue. 
I have recreated the image styles in different ways and applied them to my form approval process with similar results which makes me believe it's not directly related to the image style itself. 
I've increased the memory limit and max_execution times for testing purposes to a very high allowability. 
It is not size specific. Many larger files go through just fine, while the occasional small file size will have this issue with the image style being generated. 
It's doesn't seem to be related to the server. I've tried multiple server setups and each has eventually replicated the issue with specific images. 


Thanks in advance for helping me continue to trouble shoot this issue.
My gut is that this is a file permissions issue. Check to make sure that the webserver has the appropriate permissions for the directory in question, and the one above it.