Could anyone tell me what might be happening?
I have an orchestral template that I always use. In this last project, I added 3 audio tracks at the end, which I grouped in a track folder. But strangely, when I open this project, only the second track appears (track 88).
And strangely still, by activating the Track Manager (H), the 3 tracks appear activated (87, 88 and 89), and the track folder appears expanded, as shown below:

 
By clicking the "-" button it collapses correctly:

 
And by clicking on the "+" it expands and only then the 3 tracks appear correctly:


Could someone tell me what could be wrong?

Locked screenset?

tenfoot
Locked screenset?

Bingo!
Not screenset, but LENS!
Switching to another lens, the tracks appear.
Still, would this behavior be correct for lens? That is, some tracks disappear, even while active in Track Manager?
I think it's a BUG. 

Not a bug. Using the dropdown lense menu, go to manage lenses. There you can choose what is included in each lense. Track manager is one of the options.

tenfoot
Not a bug. Using the dropdown lense menu, go to manage lenses. There you can choose what is included in each lense. Track manager is one of the options.

The Bug I refer to is image 1 of post 1, ie how can a track be invisible in Track View while it is active in Track Manager?

The lense overrides the screenset track layout until you manually change the track layout (eg clicking the + or - on the track folder). Perhaps the track manager is not updating to reflect the track layout dictated by the lense, which seems to be working correctly. If it's a bug it's very minor:) Does the track layout appear correctly if loaded with no lense active or a lense with track manager unchecked?

tenfoot
Does the track layout appear correctly if loaded with no lense active or a lense with track manager unchecked?

Yes. So it's a minor bug... never mind...