你可能需要在两者之间留出空间 PythonExe & " " & PythonScript . 因此，您运行的命令是 "C:\…\python3.exe" "C:\…\BlackBoxAbsorbers.py" 在程序路径和python脚本之间留有空格。
还要注意 Dim PythonExe, PythonScript As String 只声明 PythonScript As String 但是 PythonExe As Variant . 在vba中，需要为每个变量指定一种类型： Dim PythonExe As String, PythonScript As String 或者是 Variant 默认情况下！
进一步的 objShell.Run PythonExe & PythonScript 无法正确调试。我建议将命令放入变量中，以便您能够在即时窗口中打印它以进行调试：

Dim Command As String
Command = PythonExe & PythonScript

Debug.Print Command

objShell.Run Command

如果执行此操作，您将看到命令的输出为：

"C:\Users\carlo\AppData\Local\Microsoft\WindowsApps\python3.exe""C:\Users\carlo\Desktop\MSc_Thesis\ML applications\BlackBox\BlackBoxAbsorbers.py"

两个字符串之间没有空格，实际上应该是：

"C:\Users\carlo\AppData\Local\Microsoft\WindowsApps\python3.exe" "C:\Users\carlo\Desktop\MSc_Thesis\ML applications\BlackBox\BlackBoxAbsorbers.py"

因此，我建议：

Public Sub RunPython()    
    Dim objShell As Object
    Set objShell = VBA.CreateObject("Wscript.Shell")

    Dim PythonExe As String
    PythonExe = """C:\Users\carlo\AppData\Local\Microsoft\WindowsApps\python3.exe""" 

    Dim PythonScript As String
    PythonScript = """C:\Users\carlo\Desktop\MSc_Thesis\ML applications\BlackBox\BlackBoxAbsorbers.py"""  

    Dim Command As String
    Command = PythonExe & " " & PythonScript

    objShell.Run Command
End Sub

解决了的！！我不明白为什么，但是拆分objshell.run pythonexe和objshell.run pythonscript效果很好！就像这样：

Public Sub RunPython()    
    Dim objShell As Object
    Set objShell = VBA.CreateObject("Wscript.Shell")

    Dim PythonExe As String
    PythonExe = """C:\Users\carlo\AppData\Local\Microsoft\WindowsApps\python3.exe""" 

    Dim PythonScript As String
    PythonScript = """C:\Users\carlo\Desktop\MSc_Thesis\ML applications\BlackBox\BlackBoxAbsorbers.py"""  

     objShell.Run PythonExe
     objShell.Run PythonScript

End Sub

无论如何谢谢@pᴇʜ，我认为你的回答是肯定的，因为你一直都很好！！