Seller Application Has Been Rejected

I tried to sell my models from this collection: CharlesSmith888 (@CharlesSmith888) - Sketchfab

But my seller application was rejected. The reason was stated as:
Model(s) do not meet our technical criteria and some of the following may need further work: topology, UVs, optimized materials, thumbnails and titles

The reasons are unclear and are too general. I don’t quite understand the exact reason for my rejection. Any help will be extremely appreciated, cause I’m at a loss right now.

As stated on our Handbook we evaluate our sellers familiarity with the viewer settings while encouraging strong emphasis on presentation skills.

Some of your models needs better thumbnail snapshots because they’re not presentable on good angles, sometimes using the default camera positioning.