Are you sure you're mining in the right spot? Do you have your best available probe on that spot? Place a booster probe next to it if you have one available.
Honestly, I left my WiiU running while I was making/eating dinner/putting kids to bed, then came back to it later that evening and it was mined.
FN Site 115, the only one I can see in Primordia with the resource available. Mining Probe G2 on it, Booster Probe beside it. :/
I play Monster Hunter, I'm used to the Desire Sensor. But this, this is getting to Ruby/Mantle levels of nuts.