The difference is the reader, but great news you can read it.
Are you getting anything on the HF side with the Proxmark3?
hf search
That is good.
Have you managed to get the LED to light up on the LF xFD using the PM3?
Also, have you seen and tried this with your fault finding?
https://forum.dangerousthings.com/t/handy-dandy-tips-and-tricks/13041/2?u=pilgrimsmaster
https://forum.dangerousthings.com/t/handy-dandy-tips-and-tricks/13041/3?u=pilgrimsmaster
Personally, I would wait 2 weeks after install (well, thats not true, I would be checking everyday, if not, a couple of times a day just like you)
After 2 weeks have elapsed, THEN I would start to consider there is an issue with the implant.