Hi Bluage,
I suspect that the double-time button you are referring to is the one that works for MIDI (as far as I know) and not RTs.
Try the following. It may well be how you are doing things but if you can be patient and follow what I have below step by step it will help narrow the problem down.
Firstly load the #1659 (organ soloist) into the String track using the following method.
1. Right-click on "Strings" (#1) and then select "Assign Realtracks" (#2).

2. When in the Realtrack Picker, click on the “#” column heading (#1) as this will sort the column numerically and make it easy to find RT #1659. Find the RT, single click on it to select it then doublecheck that the timebase is set to “Normal Time” (#2 on the image below).

3. Now “Close” the Realtrack picker using the “Close” button shown below.
4. Generate the song and let us know what happens.
Hope this helps,
Noel
P.S. The soloist will now play through the whole song. To mute it except for the 32 bars you wish it to play, use Bar settings (F5).