Another workaround:
 

1. Double-click on the reference selector that generates the error -> In the Properties window, click on the "Select" button of the “Go-to page”.
2. Choose a different page. For example, the MxModelReflection.Microflow_View, then click OK on the Properties window.
3. Re-do step 1, but now choose the MxModelReflection.MxObject_Details page.
4. The parameter mapping will be reset, and the error will be gone.

Looks like the issue only exist if you install MxModel Reflection and Excel Importer and/or Exporter in Mendix Studio Pro 10.1.1. I tested and there are no errors in earlier versions. 

I found a solution: 

1. I opened a project which I created earlier (and used these modules) and updated to 10.1.1.
2. Exported the MxModelReflection, Excel Importer and Excel Exporter modul packages from this project
3. Imported the module packages into the new project with the “Replacing Existing Module” option.

Try running Mx Reflection again to ensure all your modules, entities, and attributes are synchronized and all up to date. This should hopefully ensure the MxObjectType is what Excel Importer expects.

https://docs.mendix.com/appstore/modules/model-reflection/

I hope this helps.

I am facing the same issue, were you able to figure it out?

Hello,

Refer to this https://forum.mendix.com/link/space/studio-pro/questions/127490

Hope it helps!

Hi,

1. Make sure that you are passing the correct parameter type ('MxModelReflection.MxObjectType') to the 'MxObject_Details' page. Verify that the data you are trying to pass as a parameter matches the expected type.

2. Double-check the setup of the 'MxObject_Details' page. Ensure that the parameter is correctly defined in the page properties and that the data source or microflow associated with the page is also properly configured to receive the correct parameter type.