Have just upgraded to 26 from 25, even though I have kept 25 on the computer.

GPO5 is now not included in 26 in the score manager as an instrument choice. Have reinstalled GPO5 but 26 is still not seeing GPO5 as a choice.

Anyone have an idea how to get this working.

Am on Windows 10

Please see link https://makemusic.zendesk.com/hc/en-us/articles/217663758-Setting-up-Garritan-libraries-with-Finale-and-PrintMusic for the answer to getting GPO5 to work with Finale 26.

I have not had this problem. When you installed v26, did you install the new Aria Player? I did not reinstall the sounds, but I habitually install the Aria Player to be sure it is linked with the Finale upgrade. That may not be necessary, but I like playing it safe.

I would also check to see that you have the Garritan support files Tony mentioned in place.