I just checked Help and noticed that styles 78, 79, 80 and 81 are missing. What PAK are those in -- I believe i have installed everything including PAK 9

I'm not sure if I'm on the right track, but if you got this information by checking "What Add-Ons Do I Have", the Styles disks only go up to 77 on my system.
The MIDI Styles only go up to 77 on the PG Music Website.
Can I ask how you are identifying missing styles 78 to 81?

Bob, did you mean Realtrack sets 78-81?

Hi--thanks for helping-- I used the link in help for What Add-ons do I have......following is what it showed:

These add-ons were not found....

Styles Disks : 78 ,79 ,80 ,81
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You have all of the Soloist disks! (unless we've made some new ones)
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You have all of the RealDrums sets (unless we've made new ones).
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You have all of the RealTracks sets (unless we've made new ones).

Bob, are you running the Mac version of BiaB?

yes

Hopefully a Mac user will come along with some information.

Thanks-- I have used BIAB for a lot of years but this issue stumped me

Another question: Do you believe that you had those styles previously and now they are missing, or this is the first time you noticed that they are not available?
Maybe the Mac version is future-proofed for forthcoming styles?

I pointed this question out to the Mac section of the forum, including a link to this thread, and the suggestion was for you to go over there and ask the same question, even though the link I placed there sent the user back to this thread already.

Question about missing styles on the Mac Forum.

Hi Bob P, I am a Mac user, I have 2020 UltraPAK and just checked my version. Assuming you mean the Styles Disks, I have 0 - 77 listed.

If you mean RealTrack Sets I show 1 - 352, but I do have the extra styles disks 1 - 9, plus a few other add-ons

Hope this helps.

These are the four "Look Ma More MIDI" styles sets that we have added in the last couple years. We recently assigned them to MIDI styles sets 78 through 81. You can see them in the StylePicker if you have them. It's an error (i.e. program bug which will be fixed) that they show up as not available in the addons dialog.

Now do I fix the error

There's nothing you need to do... I clarified my post.

Many thanks Andrew for stepping in, and it's finally good to know the status and that it appears there is not a problem with the O/P's system.