Wrote is somewhere else, but don`t see artillery as units, but as artillery barrages.
Fighters represent Fighter Corps, so HQ and mobile airfields, including personnel, logistics, maintenance, and fighter groups/squadrons behind the lines.
So they act or react from their home bases, so don`t put them in front and they don`t fly like in PzC. Best is to keep them behind one or even two hexes you main battle line, closer to the front of course you have one hex more LOS (Line of Sight), but they are more vulnerable in case of a front collapses.
Same for battleships, they represent your main battleship groups, so included are all support vessels, hence a reason when they are stationary in ports or operate within home hexes(represented by green dotted hexes) they get a defence bonus representing patrol or torpedo boat and minefield protection.
Only battleship groups can bombard and support and have a max of one hex range, if your ammo production is efficient enough and they are fully supplied.
So no bugs. This is not a tactical game with individual units, unit icons represent corps or armies, naval fleets or air groups/wings with all their support. Infantry for example when they attack they have artillery support every attack, the artillery you can buy basically represent large artillery formations giving a week of continues artillery barrages before a front opens.
They don`t represent a single or a dozen guns, but a whole front opening fire for days in a row, hence the reason why your ammo is depleted after 1 million or more shells are fired during one or two weeks.
So save your ammo for well planned operations, or invest in more ammo production. You cannot shoot millions of shells every week.
Just try and get into this grand strategy mindset, of course it is all abstracted, but like this the game rules , design and concept is build up.