CentOS version 7 or newer I suppose?
This looks like an effect of
systemd session management: when the user's session ends, any processes belonging to that session are automatically terminated.
If that's the cause, the solution requires two steps. First, your user account needs a permission to let processes linger on after the user's session ends:
loginctl enable-linger <username>
Granting that permission may or may not require admin rights, depending on choices made by the system administrator and/or default settings of a particular Linux distribution.
Then you'll need to use
systemd-run instead of the old
nohup to start your long-term background process.