Thanks for your potentially very helpful post Johnathan, but even though I have exactly the same problem, your fix didn't work for me. My tempo changes, inserted into the score with the Expression tool had been working perfectly, and suddenly Playback is ignoring them and doing some other crazy stuff as well ........

For example, I saved the file with another name, and when I reopened it it now plays at a crazy fast tempo with no relation to my Expression mark tempo or any tempo that I might type into the Playback Controls box .......

Just for a lark, check that your audio sample rate is consistent between Finale and your sound card. Either have both set at 41K or 48K. A mismatch (which could be inadvertently caused by another program) would also slightly change your pitch.

Any time something suddenly stops working, my first action is to reboot the computer.

And I had a repeat of the same problem - but found a different solution ...... Other files WERE playing back with their tempo changes so I knew it was a file-specific problem. The solution was to make the tempo changes (expression tool) visible on all the staves. When they only showed on one stave, they were, suddenly one day, not "read" by Finale...... 

I post this just in case anybody else finds themselves with the same problem .....

Finale reads tempo marks in the top line only... if you're in a staff set without the top line of the score, you'll get random errors.
You might get other errors for various reasons. It's a particular issue when trying to export audio stems from your score.
2 solutions:
1. Midi Tool>Apply Human Playback> select "Apply Specific Elements>Tempo Changes" before export or playback, even in a staff set,
2. Select all (or whatever you're trying to chage), then Midi Tool>Tempo, then Midi Tool> Set To...
Tempo data set with the midi tool will take precedence over any other attempt by Finale to calculate tempo via Human Playback... make sure you have Preferences>Human Playback>MIDI Data >Tempo set to HP (Incorporate Data).

It's a sure-fire solution to use the MIDI tool to override HP interpretation errors. You can even create custom fermata lengths and rits that stay with the file and any export.

See the article https://www.scoringnotes.com/tutorials/using-finales-tempo-map/ 

… The solution was to make the tempo changes (expression tool) visible on all the staves …

Ian Swedlund,

The general solution is this:

Document menu > Category Designer > Tempo Marks > Score List > Edit…

In the Parts column, check all staves.

Did you try that?

(Yes, I know. It sounds crazy that a setting for parts would affect playback of the score)

Thanks Peter and Jonathan - I will guard preciously your solutions for the next time this happens !!

Yes, Peter, that was my fix, but I got there via double-clicking on the score with the Expression Tool highlighted but it was pure luck that I clicked on the Parts as well as the Score. Now I've learnt another trick - thanks!

I tried all these suggestions, but Ian's was the only one that worked. It looks terrible in the score. But otherwise, it doesn't work.

I have tried all these fixes and nothing has changed the tempo.  I am adjusting the tempo in the playback ribbon and it will not change at all.  It has to be a problem with this file because I can change the tempo on other pieces using the playback ribbon.

Setting the tempo in the playback window only sets the starting tempo. Use the expression tool to enter any further changes in the score.

If a single file is,causing,trouble, export it as XML, and then import it back in. That often will clear up unseen file corruption.

Thanks Mike. Finale was reading and playing back my tempo changes but the exported audio didn't have those tempo changes. A computer reboot solved the problem .... !

You've just saved my ass on a really tight deadline, thank you