Several people have not been able to upload Mesh in ADITI, the preview grid, but they can in AGNI, the main grid. Most often this is because they have not run through the Intellectual Property thing for ADITI. Yes, you have to do it twice, once for AGNI and once for ADITI. For ADITI visit: https://secondlife.aditi.lindenlab.com/
Also, after viewer and server updates some people are crashing when the attempt to tp to the mesh sandboxes. See: VWR-26698
Also, the 3.0.0 has a video gotcha that causes some people problems. If you are having a problem, visit the Snowstorm Page and get a copy of the latest development viewer. There are some video fixes included that have helped some users.
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