Mac Not Recognizing FreeAgent after format?

I am a recent PC convert. I have been using a Seagate Freeagent Go Flex ultraportable on the Mac for awhile now, using Tuxera to enable writing.

I experienced the common problem of the disk randomly ejecting for seemingly no reason. Got the red stop sign.

This had happened times before but this time I could never get my Mac to recognize it again.

I backed my drive up on a Windows machine and formatted it to exFat in hopes that my Mac would play nicer with it. It still won't read at all. The machine doesn't recognize it in anyway.

Please help!

 

I tried formatting it back to NTFS on a PC to see if the Mac would read it in its default state.

I plugged it in and boom, there it came. Time Machine asked if I wanted to use it for back up. I said I'd decide later, ejected it and left.

When I plugged it back in later, same thing. It won't read.