Possible bug - stuck Pangea recruitment

[Networkingguru]

My wife has been playing Pangea, and she has had the case several times now in which a unit that has been purchase in her capital will not build. She goes to end turn, everything seems fine, but when she looks in her queue, the unit is still there. This only happens after the early part of the game, otherwise it is random. But once it happens, no more recruitment in that province ever takes place. She does have enough resouces to recruit the unit, and it does not seem to be unit specific.

Is this a known issue? It seems to be pretty repeatable, so I am sure I can get a save file if needed.

TIA