Select Members of Group 39

Select all channels that are members of group 39. This is not possible. There are only 32 groups.

Overview of groups in Logic Pro — Apple Support

Prior to mixing, you may find it useful to define some logical channel strip groups. You could, for example, group all drum channel strips under one drum group. This would allow you to control the group meters (volume, pan, mute, solo, sends, and so on) using a single control, while still maintaining the relative parameter values of each channel strip.