My investigations lead me to consider it a Xylobium.
There are several thread in the forum about them but are too old and with not many information.
Anyway, if this is a Xylobium it will turn into a massive plant, with leaves between 20 and 40 in in length (0,5 to 1 m). In fact the new growth (the second from this pbulb since I got it) is has now the double size of the first.