I have used the same title as a previous question as it describes exactly my problem.
MacOS Catalina 10.15 (19A583)
iOS 13.1.3 (17A878)
I have Voice Memos switched on in the iCloud settings on the iPhone.
I have Voice Memos switched on in the iCloud Drive options on the MacBook Pro.
I am signed in to the same AppleID on both devices.
I regularly record Voice Memos on the iPhone.
My latest Voice Memo on the mac is in March.
The above settings have not changed since before March.
There is ample free space in my iCloud Drive.