I have the same problem with administrator (you have admin login data) or other user role.
I tried on several computers, three browsers, and three user roles... Definitely not related to the user role.
I think is related to the size of the images...
Or it is related to time during creating thumbnail in Media Library, or maybe upload time...
I've seen your images from test CPTs, they are a few hundred kilobytes, and without big resolution.
I' don't have a problem with very small images, but images bigger than 10 megapixels (cca 3MB) produce Internal Error 500).
Likely users will upload bigger images than a few MB what will generate a problem and make this form useless.
Please could you try with bigger images, and see in CPT does it upload under "featured image" and "other images"?
In my case, from field "other images" uploads are there (even if they are bigger than a few MBs) but the "featured image" does not upload.
It seems that problem is solved! Third try with BlueHost support.
Tested three times with bigger images and works...
The supporter told me that he changed some PHP settings and cleared the server cache...
Thank you for your effort!
Will see it will work further....
Thanks for the update and glad that this is fixed now.
If you could also share, exactly which PHP setting needed adjustment, it would be very helpful for other users who may experience the same issue.
Please feel free to mark this ticket as resolved and start a new one for each new question or concern.
