I never use Users folder (we have an expression for that folder).
And as for the rest of the file path... can we squeeze any more punctuation in there!
In a 'normal', simple path. No problem
Try putting the file in a different location.
pth = r"C:\Git_Dan\arraytools\array_tools_testing\array_tools.aprx"
import arcpy
p = arcpy.mp.ArcGISProject(pth)
dir(p)
Out[275]: ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__',
.... snip.... 'activeMap', 'dateSaved', 'defaultGeodatabase', 'defaultToolbox',
'documentVersion', 'filePath', 'homeFolder', 'importDocument', 'listBrokenDataSources',
'listColorRamps', 'listLayouts', 'listMaps', 'listReports', 'save', 'saveACopy',
'updateConnectionProperties']
Spyder latest version 3.3.2
python 3.6.6 64 bit
ArcGIS PRO Beta 2.3 (although that doesn't make a difference)