As always, restart the computer.

Export the score as an XML, and re-import.

If that doesn't help, recreate the preferences.

Dear Mike,

Thanks very  much for the swift reply.  Re-importing the XML does not fix the empty staff problem, and messes up a huge amount of other detail in the process.

I reset preferences and re-opened the file, and the empty staves still will not hide.  Any other ideas?

Maybe add a new staff, and copy the content. Then, delete the original.

The only other suggestion I would have would be to send it in to Finale. Use the Submit a Request link at the top of the page.

Thanks for that.  I've asked Finale.  

… the empty staves still will not hide.  Any other ideas? …

1) Take a look at the Staff Attributes for a “trouble staff”.

Is the option “Allow Hiding When Empty” selected or de-selected?

2) The culprit could be a staff style in the empty measures.

Try this:

Staff menu > Show Staff Styles (select this)

Staff menu > Show Staff Style Names (select this)

Now you can see the staff styles.

Do not worry!

The staff styles will only show when you are in the Staff Tool.

With all parameters correctly defined (empty measures, staff and group attributes, no staff styles) I had a similar problem a while ago, so I consulted MakeMusic, and the solution was in this case to select only the staff I wanted to hide and apply "Hide Empty Staves". Strangely, it wouldn't work if I selected the whole system, which is abnormal. Try that...

I'm having the same problem. Were you ever able to solve the problem, George?

BTW, I've had other problems with the more recent versions of Finale in the past several years and the go-to "fix" the support people seem to use is to delete default files and throw away all preferences. This has never helped me. Since it also inconveniences me greatly, I'm hoping you found some other fix. I'm reluctant to throw away preferences again... 

(Using Finale 25.5.0.259  on an iMac with OS 10.13.6)

Just a quick follow up:
When zooming in to work on a detail, I happened to notice that the curly bracket of the grand staff I'm using in this piece looked like it might have been doubled. In fact, it was. For some odd reason there were two measure groups doing the same thing (hence the doubled staff bracket). After I deleted one of the groups, it occurred to me that maybe the doubled bracket was influencing my ability to hide staves. Turns out, that WAS the culprit! After I removed one of the groups, I could hide empty staves. I'm not sure if this would relate to you problem, George, but just in case it does, I'll post it here.