The fact that neither the iPhone nor the iPad show up in Finder suggests a settings issue.
There are two Finder preferences to check:
One is the CDs, DVDs and iPods box in Finder > Preferences > General tab.
The other is the CDs, DVDs and iOS Devices box in the Finder > Preferences >Sidebar tab.
If you've confirmed that both of these are check marked, try rebooting the Mac.
If that doesn't resolve the problem, see if the problem still happens in Safe mode (hold the shift key down at startup). It can take much longer to safe boot (10 min) so be patient. How to use safe mode on your Mac - Apple Support
Safe mode forces the OS to clear certain caches and logs and do other miscellaneous housekeeping. It's non-destructive to user data so is safe to do. Very often certain weird software behavior is corrected by simply logging in this way as a troubleshooting method. When you're in safe boot, the machine will not be at its best performance, especially with graphics, but that's expected.
Does the problem persist while in Safe mode?
Exit safe mode by restarting your Mac normally and re-evaluate the issue again.
If the problem is still unresolved, please return here and post a reply and we’ll see what else we can come up with for help.