I can create a new Blueprint asset with no issue. I can make any changes/settings to the blueprint. After I save and close the window the thumbnail looks correct. When I reopen the asset all i get is the toolbar. I thought it was just a one time thing, but I started another new project and receive them same results. Any ideas?
Do you have any additional plugins installed?
If so, try to remove/disable them, this has fixed these kinds of issues before.