This is a problem related to restricted servers and “auto” height grid items.
To be able to detect image proportions, Media Grid gets WordPress image’s data that normally are recorded during upload.
Unfortunately restricted servers sometimes deny the access to these infos, then WordPress doesn’t store any data.
Direct consequence is the inability to create “auto” height proportions, then is not possible to use this setup.
Only solutions are to use a fixed height value in grid builder or unlock the server and upload again the image.