@Jorge_G 

Hi,

The Bluetooth part of the TX55E doesn't depend so much on the particular PCIe slot, but on the USB port.

If you have more than one internal USB connector on your motherboard, then check if anything changes if you plug the supplied USB cable in another USB port.

And while you are at it also have a good look at the cable itself. Verify that none of the four wires has come loose and that the wires are in the correct order. (below is an example of a similar cable)
 

  @Jorge_G  Thanks for your answer!

Unfortunately the cable didn't come with the USB cable you show me, do you know if this is selling as spare?

  @Jorge_G 

If you bought the TX55E as brand new, then you should definitely ask whoever sold it to you to supply you the USB cable.

The thing is that while the black connector seen in the lower part of the picture is standardized, the other connector that plugs directly into the TX55E is not. Therefore it will be difficult to buy a cable with the correct connector that fits the TX55E. 

But you can try you luck, if you wish.
https://www.google.com/search?q=USB+Bluetooth+Cable+4-pin+to+9-pin&tbm=isch