Have you tried restarting the computer? Very often, when something used to work but now it doesn’t, that’s a great place to start.

… I've got D.S. al Coda in my score, but I can't get it to show up in anything *other* than the top staff …

Two things to try:

1) Staff Tool.

Double-click a staff to get to the Staff Attributes.

When you are in the Staff Attributes, you can “cycle” through the staves via the pop up menu at the top.

For each staff, look in the pane {Items to Display}, and make sure that the option {Endings and Text Repeats} is selected.

NB:

The culprit could also be a staff style - since a staff style can change the staff attributes “locally”.

2) Repeat Tool.

On the handle of the D.S. al Coda, right-click, and in the context menu choose “Edit Repeat Assignment…” (or double-click the handle).

You get to the dialog box Text Repeat Assignment.

Examine the bottom pane {Show On}.