AutoHotkey Not Working
AutoHotkey did not work with Everything. While it worked normally everywhere else, it just wouldn't work with Everything.
With Other Tools Too
This issue also occurred with other applications. (Search rank GRC) It used to work before, but suddenly stopped. Possible cause... an update?
It Worked After Restarting
GRC worked after restarting. But Everything still didn't work.
The Cause Was “Administrator Privileges”
Everything, due to its specifications, needs to always run with administrator privileges (apparently). That's why it didn't work.
When I tried running GRC with administrator privileges, it indeed didn't work.