Losing taxonomy while adding a translation

Hi!
I have a weird problem for which I have found nothing similar in the queue.

Two of my content types use taxonomy. When I try to add a translation to one of these nodes (via Translate tab), the new node has no taxonomy, I mean, the form has no taxonomy menu and if I submit this node, there's taxonomy when I try t edit it.

Following some advice found in issues here, I activated the Synchronize translations module but that didn't change a thing.
Any pointers?

Thanks!
Ricardo