If you use LDAC, Mobius defaults to HiRes connection only and disables the 3D (presumably something to do with the data transmission and processing requirements) - this is hard coded and can't be changed, so you basically can't use 3D with LDAC Bluetooth. If I want 3D audio via my phone via BT, I just go into the advanced settings on my phone handset and select one of the "midrange" BT code like AptX (can't remember if AptX HD or just standard off the top of my head). That brings the usual voice menus back, and allows full 3D function with good resolution.
You can use ldac and 3d, just need to set the mobius to 2 channel mode by setting developer bluetooth rates to 16bit and 44khz or 48khz, you can select the highest playback quality as well. You only cant use 3d when you set ldac to 24bit/96khz, which puts the mobius in high res mode