Another thing.......the Ragnarok was engineered and built in Esthar. Its wouldn't surprise me if Esthar built their spaceship with the technology that allowed it to pass through their barriers.

For instance, maybe the Ragnarok alters the frequency of its shields to match the frequency of the energy field around Esthar so that it can pass through. (Kinda like in Star Trek, when "Picard/Janeway/Cisco/etc" has to fight an enemy for the first time, if they can't penetrate the shields right away, they sometimes find a way to alter their weapon frequencies to match that of the enemy's shields, so they penetrate the shields.) It IS a high-tech space ship, after all.

There are many possibilities. Something like what I stated above, or a proramming convenience. I certainly don't think its a "bug". It doesn't seem like a bug, the way the ship passes so flawlessly through the barrier, as if it wasn't even there.