Minutement Can't Use Roads

[Proteus_MST]

We know that upon upgrade units retain their abilities from their past unit status, even abilities that were unique to their former unit status (for example scouts that upgrade through ruins to archers still have their scout movement abilities)
Maybe this is the cause of the bug... i.e. having to set up before firing is counted as an (invisible) ability that therefore is preserved during upgrade

[snafuc4]

Maybe a mortar team or something that crossbows could upgrade to.

Mortar team sounds like a fine adition to me! Minimal H2H combat + indirect fire at low range

[Louis XXIV]

Yeah, Mortar is easy and an obvious choice. It's the early gunpowder era that's left me at a loss.