I'm having issues uploading attachments that I'd already uploaded before just fine before the most recent update.
I get an "Asset's center is outside of the bounding box" error if I give the attachment the proper rotation it needs to be on the correct spot. In Blender we have to do this by rotating by 90 degrees on the X axis, so that the model looks like it's on the ground behind the avatar.
However, if I leave it with the wrong rotation, the model uploads correctly without errors, but is then sitting in front of the avatar on the ground after upload.
In the first shot you see what it looks like after uploading without the 90 degree rotation. The second shot shows you what that looks like in Blender before export.
This honestly seems totally bugged to me. It's complaining about the center when it shouldn't, and not complaining about it when it should. It's uploading the model without errors only by putting it on the ground in front of the avatar. If I rotate it so that it's attached to the torso as it should, it spits out the error again.
UPDATE: I resolved the issue by exporting the FBX as FBX Binary, instead of ASCII, and turning on the "EXPERIMENTAL - Apply Transform" setting in the Blender FBX Export options. Then I had to resize the attachment by .01 scale. I guess Sansar doesn't like ASCII FBX much for attachments? (ASCII works fine for me for everything else)