Have you checked these first?
Help us help you: include your environment details. We've made this easy for you. Use the Copy System Info button in Admin Panel › osAwesome › Diagnostics, then paste below.
Note: Never paste the contents of your ost-config.php file here; it holds your database credentials.
Two quick checks before posting: try clearing your browser cache, and press SHIFT+O on any Staff Panel page to enter Safe Mode (a stock osTicket with no enhancements). If the problem still shows in Safe Mode, it's in osTicket itself, not osTicket Awesome. But let us know about the issue either way.
Help us help you: include your environment details. We've made this easy for you. Use the Copy System Info button in Admin Panel › osAwesome › Diagnostics, then paste below.
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The attachment preview plugin can not work in version 1.18.1 Rev01.
Can not show PDF files inline.

Same issue.
Hello Stev.
This plugin is very important for our business.
Can you help us??
Thanks
Hi guys,
If you switch to vanilla osTicket by pressing SHIFT + O you will see that this is not an osTicket Awesome issue.

See also:
https://github.com/clonemeagain/attachment_preview/issues/63
Hi everyone,
We found a temporary solution for this bug, simply install this plugin in Chrome or Edge:
https://chromewebstore.google.com/detail/pdf-viewer/oemmndcbldboiebfnladdacbdfmadadm
After install you must allow the active content (javascript) and File URL permission in the plugin's settings.
Change:
include/client/header.inc.php
include/staff/header.inc.php
