I’m not particularly familiar with Paxton.
I think it is a High Frequency system and I also think it is compatible with a Mifare Classic implant.
xM1
FlexM1
I’m not sure about the NExT. 
It doesn’t sound like you have a Proxmark3, but if you do can you try either
lf search
or
hf search
If it is HF and you don’t have a ProxMark3.
Can you try and scan you fob with TagInfo and share your results here