If there is no apparent answer from the MRI, etc., it seems like an enigma.
I have continuing pain in my butt (and down to my ankle), but the cause is evident from the MRI and X ray. I am considering the insertion of a rod and screws in the L 4/5. I'm told that it is a "simple operation," (I've heard that before.) 🤔
Last oct (1019) I had discectomy on the L 4/5. Unfortunately there is currently a compression on the the L 4/5 nerve; I suspect that my be your issue.
PT never helped, often causing more pain; tough to find a great PT who follow your needs rather than their procedure.
Best of luck to you and all of the rest of us.st of luck