Is this a bug with B team?

I have signed a number of free transfers while trying out a B team save in the Spanish lower tiers yet during every friendly the players signed are all "Unavailable". There is no explanation as to why this is the case, I checked the registration and squad numbers and hardly anyone has squad numbers and a couple of these players are registered although the season hasn't begun yet. Surely these players should be available for friendlies or is it a bug?