What am I doing wrong?

Before I could double click on Page 1, Page 2, etc and access the many layers.

Or I could click on the image and drill down into the group of layers.

Now for some reason, I can't.

They're not locked.

It's simple probably, but man - I can't work it out.

Look at my red arrow

Thanks Monsterfox.

I clicked both the minus and plus buttons multiple times yesterday but got nothing.

Today, I open the document and all is working properly.

Perhaps it was a system restart. Perhaps it was your red arrow.

Appreciate your help : )