Since some time (about a year I suggest) Acrobat Reader does not show my 3D PDFs correctly anymore (on former versions this was OK) - first picture is from an actual Acrobat Reader, second picture is from an old Acrobat Pro version (former versions of Acrobat Reader did show it correctly as well).
I hope you're doing great, and sorry for the issue you're experiencing.
As described, the 3D content of your pdf is showing wrong. What is the Acrobat Reader version you are using? To check the version, please go to Help > Check for Updates.
Make sure you have the latest version installed. Go to Help > Check for Updates.
Also, is the issue file specific? If possible, could you share the sample file with us so we can reproduce the workflow at our end and check?
Also, you may refer to the steps provided in the help article: https://helpx.adobe.com/acrobat/using/displaying-3d-models-pdfs.html and see if that helps.
Hoping to hear from you soon.