[PvK]

I think the problem is probably the "break formation" settings. If your "Ignore Planet" strategy has fighters or ships break formation, then they will use the strategy listed in their design.

"Don't Fire On Planets" does work and does include the weapon platforms, if any (i.e., if they are obeying that tactic, they won't fire at planets at all, even if they have WP's). Only the "Drop Troops" tactic cares if there are weapon platforms (if you have ships and they have WP's, your ships will try to kill the WP's before dropping troops).

PvK