Is it a node (i.e. a wire) or a device terminal that you are selecting? Obviously selecting a node makes no sense...
Note that saving device currents only saves currents on primitive devices; if the terminal you are probing is a subckt terminal (and that includes if the model is implemented as a subckt underneath), it will not be saved.
You can get them to be saved by using the subcktprobelvl option to save currents to a certain depth; be warned that this can impact performance because it causes lots of iprobes to be inserted which makes the matrix bigger (this can be avoided using the subcktiprobes option - see "spectre -h options")