If you have a PDF file with a .docx .xlsx or any other file format embedded within it it’s possible it wont open due to some security settings in the registry.
Edit the tBuiltInPermList key:
To modify the level of user access to file types:
In the Add and Modify File Types (Extensions) list, scroll to the file type you want to modify.
Set the user access level when opening or launching the file type to one of the following:
- Unspecified: Sets tBuiltInPermList to 1.
- Allowed: Sets tBuiltInPermList to 2.
- Prohibited: Sets tBuiltInPermList to 3.
This feature sets:
[HKLMSOFTWAREPoliciesAdobe<product name><version>FeatureLockDowncDefaultLaunchAttachmentPerms "tBuiltInPermList"