Error while trying to package multiple maps

[MattMoy]

Hey Esri Community, 

I've been trying to use ModelBuilder to package multiple maps but keep receiving Error 000260. Does anyone know how to resolve this issue?

The model I've created is based on this Esri article: How To: Package Multiple Map Documents in a Single Run in ArcGIS Pro (esri.com)

I've created the same model, added my inputs, and checked the Package Map step to ensure that the only input is Value. But everytime I run the model I receive the error shown below. Any ideas?