When adding a manual route to a dhcp configured eth interface managed by
wicked, the dhcp setup fails with a silly message:

device enp7s0 failed: "call to
org.opensuse.Network.Addrconf.ipv4.static.requestLease failed: General failure"

Add a manual route to a dhcp configured interface and restart your system.
Be prepared, that this interface will not come up correctly.

BTW: the routing editor allows selecting configured interfaces only. The usual
order is: setup interface, add route, but you have to confirm the interface
setup first, reenter yast network and add the interface based route there
after.