Plastic,
There have been no changes to missile detection and no significant changes to the NPR design code (except carriers) between v6.43 and v7.10. If there was a problem with missiles not being detected I would be getting a LOT of bug reports to that effect. I haven't seen any. NPRs and even spoilers can be very different from game to game, especially if you meet them deep into the game, so you may be seeing aliens at the upper end of the random range.
A lot of people are trying to help and you seem to resent that help on the basis that we must think you are not very smart if you need help. That simply isn't the case. This is a hard game to learn and play and everyone needs help. This is probably the most polite and helpful forum on the internet so please don't take offers of help or advice as an attack.
As many people have stated, post your ship designs. You may find that your issues are due to some easily-overlooked problem that experienced players will spot immediately.
SM is short for Spacemaster, which is similar to a dungeon master in a role-playing game. As Aurora is primarily a solo game you will need to be the Spacemaster to setup the game and become the player to play it. The game is intended to played with a Trans-Newtonian start, with some basic tech and a few starting ships. You have a set number of points for tech and a set number of points for starting ships, depending on your population, You will need to use SM mode to spend them before the game begins. All the NPRs are setup on this basis.
A conventional start is effectively 'Advanced Mode' for Aurora as you are giving yourself a significant disadvantage vs. the NPRs. If you run into an alien race after 38 years (which is a long time into the game), there is a good chance it will be a fairly advanced race.
NPRs use the same rules for ship design and combat as you do. The only exceptions is that NPRs do not need fuel or maintenance, although their ships are designed as if they do. They have the same limitations on missile capacity (and have to reload) and the same armour as you do. Something else to consider is which options you are using. If you have Invaders on, they will have very advanced ships from game start. Also, most players (myself included) simply stay out of the way of advanced aliens until we have sufficient technology or numbers to overcome them. Sometimes, the bad guys are just too powerful and you have to retreat.