Before Dante Unbound, Vauban's tap/hold inversion was apparently bugged. The option inverted Minelayer but it didn't invert Bastille. Now, Bastille respects the invert option such that, if you pick inverted, Vauban will throw a Vortex if you tap, and a Bastille if you hold. However, holding the ability button again while a Bastille is out on the field will turn that Bastille into a Vortex instead of throwing another Bastille.
This means that it's only currently possible to have more than one Bastille (the lifting, armor stripping part of the ability, not the Vortex) on the field if you pick standard settings instead of inverted.