Trying to export my model to be viewed online or in a different software. The model itself is too large of a file size for me to export to sketchfab, and when i export it as a .obj file it opens up as an empty 3d space, and is almost 5 gb. I've read about decimating the mesh and all that to make it smaller, but in the tools>mesh menu, all of the options including decimate mesh are greyed out. Not sure what I'm doing wrong!