Hi Marten,
I have tried the following things like
1. Making the MyProfile (Data) profile unique by setting the type definition as the first one in MetadataEditor.js
2. When I remove the tab E-Commerce, I'm able to save my data in Myprofile (Data)
I have attached my geoportal gxe folder here for your reference. please help me to figure out what's stopping me to save the Myprofile (Data) metadata profile. Error screenshot is also attached. looking forward to hear from you and let me know if you need anything else for debugging this issue.