Files not uploading due to 'Server Forbidden'

Nextcloud version (eg, 10.0.2): 12
Operating system and version (eg, Ubuntu 16.04): ubuntu 16.04
Apache or nginx version (eg, Apache 2.4.25): unknown
PHP version (eg, 5.6): unknown
Is this the first time you’ve seen this error?: yes

Can you reliably replicate it? (If so, please outline steps):

The issue you are facing: A portion of my files are not syncing from the Nextcloud desktop app to my shared hosting site. There doesn’t seem to be a rhyme or reason to the types of files. So far MP3 MOV WMV PDF ODF files are showing an error. On the activity page of the desktop client it reads:

"Error Downloading “http://…/nextcloud/remote.php/dav/uploads/admin/randomnumber/000000000”

The output of your Nextcloud log in Admin > Logging:

07-30 20:28:23:947 26523 OCC::createBlacklistEntry: Probably firewall error: 403 , blacklisting up to 1h only
07-30 20:28:23:949 26523 OCC::SyncJournalDb::updateErrorBlacklistEntry: set blacklist entry for “OneNotes/CourseRA/JH” 3 “Error downloading - server replied: Forbidden” 1501460903 625 1498502840 “” “”

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

The output of your Apache/nginx/system log in /var/log/____: