I have always used the Celtic SlowWaltz guitar for songs... I just updated to 2018 and that instrument does not show up now on the style. The folder under RT has that guitar ("1815") I re-loaded the download and everything but that one guitar shows up ... what am I missing? How do I get that to work?

If you go to the RealTracks picker, enter 1815 in the filter, press Update, do you see the track there?
Also, try Rebuild and Fix?

It does not show up anymore...

I reloaded #173 which has two guitars the other a 4/4 #1814 and it is there but not the waltz.... I thought maybe it means that I have to have another style to make it work BUT I have about 30 backing tracks created using that guitar #1815... before I loaded the upgrade to 2018. I am totally confused.

The folder says it was updated yesterday .. and it has several files in it:
ag2561-2575 ...wma files. I've rebuilt several times.

1815 works just fine here with 2018. I suggest contacting PG Music Support.

Just so that I can get a clearer picture of your situation in my mind, could you please answer the following questions...

When you say you 'updated', how did you do this?

What package did you purchase to update with?

Are both BIAB and Realtracks installed on your computer's internal hard drive?

Did you install the new version of the program over your old version (that is, in the same folder as your previous version)?

Regards,
Noel

Just started a "chat" with live help.
Went from 2016 to 2018 BIAB [PRO], Reloaded Set #173, Yes both are on internal drive, Yes did the same folder over the old.

Thanks for the extra info.

Live Chat might have solved your problem by now... if not, though, something that has worked for a couple of people with similar problems as yours is as follows.

1. Log-in into your sales account.

2. Go to "My Products".

3. Scroll down a bit and you'll see all the files that are available with your purchase. Download the the installation file that contains set 173 and install that.

Sometimes getting the latest version of the installation file seems to contain what appears to be missing from the original installation file.

Regards,
Noel

Re installed EVERYTHING and is now working again YEAH ... thanks for all help!

Good news! PG support staff is really good.

Excellent, thank for letting us know it's resolved, and the method that did the trick.