The iPad's orientation before you select an album from Browse mode seems to make a difference (I believe someone pointed that out in the other thread too). Landscape: Play Pick Tracks is not available, even if the album has Pick tracks. Portrait: the Play Pick Tracks option is active, however as Carl points out, it doesn't do what it's supposed to. For me it always adds all but the skip tracks to the queue.

Soundserge

Antipodes CX + Roon, 818v3, DSP 7200SEs, 218, DSP3200s