Angus,

What you're doing is not cross-staff, but rather, beaming across the barline. I'm not sure what the problem might be. Are you using the Patterson Lite plugin, that comes with the program? If so, are you selecting the three notes, before you apply it?

Since you're using Mac 10.13, you should consider upgrading to F25, as well, although I don't think that's the problem.

It might help if you give us a complete description of how you are trying to do this.

Try this:

https://www.finalemusic.com/blog/finale-quicktips-cross-staff-beaming/

If this doesn't work, it may be becauseFinale 2014.5 is not supported in High Sierra and it's time to upgrade.

The normal issues are the same as in Sierra. 

https://makemusic.zendesk.com/hc/en-us/articles/227137247

Use Robert Patterson's beam over barlines plug-in found at Plug-ins>Note, Beam and Rest Editing>Patterson Plug-ins Lite> Beam over barlines.

First, with the Selection tool, select just the area you want beamed together (in this case the last quarter and first eighth of the following measure) then invoke the plug-in. It will connect the beams across the barline.

… First, with the Selection tool, select just the area you want beamed together (in this case the last quarter and first eighth of the following measure) …

In my experience there is no need to select so precisely.

Just select those two measures, and the plug-in will beam over the barline.

The other notes (at the beginning of the first measure, and at the end of the second measure) will not be affected.

By The Way:

The plug-in uses one method when beaming over a barline inside a system, and a different method when beaming over a system break.

If you re-arrange the measures so that the first measure ends a system, and the second measure begins the following system, then the plug-in will use the other method.

Hi again. Thanks for your help and suggestions. There are 4 instances where I want to beam over the bar line, and as you can see in the attached screen shot, I received 4 different solutions from the Paterson plug in, only one being successful. Maybe I should delete the music from the measures and re enter it?

Thanks again for your help.

Angus

Where you see the grey notes is an artifact from the plug in. If you go to the View menu and choose to not show hidden notes and rests, the notes will appear correctly.

Try the {across system break} method.

When you have run the plug-in, the solution will stay the same, even if you re-arrange the measures so that the beaming no longer goes across a system break

Hi and thanks to everyone who sent suggestions for my issue. What I finally did, was to erase the music in these measures, delete the measures, then I inserted the same number of measures, and then reinserted the notes using simple entry. After all that, it worked fine. There must have been some hidden objects that were obstructing what I was trying to do.

Thanks again

Angus