Steps to try:
1. Publish all customizations. Simple, I know. But sometimes people do things quickly and forget to publish all. Ctrl+F5 to do a hard refresh afterwards too.
2. Use the classic editor - go to Advanced Setting and open your solution from there and then open the security role. See if the tables are there now.
3. As stated in another reply, your table will only show up as long as it’s not an Activity table. If it’s an activity table, all permissions fall under Activities permissions.
4. If all else fails, create a new security role and see if your table shows up. Sometimes the security roles do strange things.
hope that helps!