I have a similar issue:
I have a base slide named 1.2 with two layers (Layer 1, Layer 2). Layer 2 of Slide 1.2 links to the base slide 1.3, which contains three layers (Layer 1, Layer 2, Layer 3). The entire course is designed with custom navigation buttons from my client's graphic line, where the 'back' button on slide base 1.3 should logically return me to Layer 2 of slide 1.2 because of the course's context and the order I've given it. Since I can't make it return to that Layer 2 of Slide 1.2, I must link it to base slide 1.2 instead, and the user, by default, must revisit the content of base slide 1.2 and its layers. What can I do?