… Finale 26.3.1.643 (Mac OS 11.6.1) …

With the exact same combination of Finale version and Mac OS version I am unable to reproduce your problem as you describe it.

In a measure where the first half of the measure has slurred notes, the slurs do not disappear when staff style Slash Notation is applied to the second half of the measure.

Can you provide exact steps to reproduce the problem?

I'm applying the staff style Slash Notation in the usual way. As soon as I do, the previous slur disappears.

Interestingly, I see in my Define Styles dialogue box that the boxes for displaying smart shapes are unavailable:

I reproduced your example:

As you can see, the slur appears for me, both with and without Slash Notation.

What is interesting, is also that your example shows another smart shape - diminuendo hairpin - which does appear.

Hmm…. I wonder what's not working for me.

One other twist to this: playback of the (now-hidden) slurred notes becomes detached as soon as I apply slash style.

Later, when trying to create multi-measure rests, I experienced more glitches. This made me step back and think: this file began its Finale life as an XML file exported from Dorico 3.5. I'm beginning to wonder if all of these odd behaviors I've not encountered before might be XML import-related.

Hello!
Has there been any development in finding a solution to the problem exposed in this thread?
I am encountering the exact same issue with Finale 27.4.1.146 (Mac OS 10.15.7), working on a file that was not imported, as it was created with Finale from the start.
In the two attached screenshots I show that once I apply the Slash Notation staff style to the second, third, and fourth beat of the bar the slur running from the first to the last note of the bar disappears.
As Judd pointed out, the Alternate Notation settings do not allow the showing of smart shapes such as slurs, since the option is greyed out as shown by Judd's screenshot. Any suggestions?
Thanks for the help!

Krishna

You may just have to add it manually. Obviously, there will be no fixes or updates to Finale.

Thanks Mike!
Yeah, I wasn't hoping for future official fixes since we're now totally on our own terms.
I was however hoping I would not have to add slurs manually, as there's quite a few of them in the score, but alas, this seems to be so far the only way around.