I thought it was a problem of them or the corsair ship being on bridges, but apparently, it wasn't, since after deleting the bridges and setting it up like this:
It's still not able to be used.
Edit: just noticed I posted it in Game instead of Units/techs/effects, sorry, should I delete this one and reopen it there or should I wait for it to be moved?
Green is the correct color, other colors are "less correct".
I moved it to unit balancing, as effect works exactly like I intended to implement it - ergo - no issue.
But it's whole another topic if this ability really makes sense.
Sell Other Ship ability is set to be used for getting rid of unneeded ships after converting them.
Possible sacrifices are [Ship], excluding [Valuables].
And it was not my first choice. Original idea was to get some sort of valuables from sacking enemy (by melee attack).
Merchant ship here is just a representation of valuables/cargo from that.
Main reason why valuables are excluded is to stop using it on Merchant ships.
Oh, thought that was a bug, now it makes sense, thanks. I'm not sure if it should be changed, I just had a situation where I had some valuables near water and thought of trying this, but if that is not the intended usage of the skill, then I think it might be fine, I'll try using it on unneeded ships and see how it does.
Green is the correct color, other colors are "less correct".