So, last night I had a dream that a friend of mine and I were in a zombie-infested post-apocalyptic wasteland based off Left 4 Dead. Twice in the dream a zombie is about to either infect or kill me and I suddenly think “Hey, I’m dreaming; I can’t die!” Then something completely irrationally miraculous happens and saves me. The HUGE issue is that afterward, despite thinking that I was dreaming inside the dream, I don’t achieve lucidity. And this happened twice in one dream. Any advice on this issue?
Well, congratulations first: it seems like you had lots of fun ^^
Secondly, did you have any precise goal to do while lucid? Those can help a lot with reaching enough lucidity to accomplish them. And if you did, would you have chosen them over the story you were experiencing? If you were having fun enough, it’s possible you didn’t want that dream to end or deviate, and so you just kept going 
But no worries, things like this can happen, they’re called low-lucids: it still is a step forward in your lucid skills 
Indeed, I had a precise goal to try shapeshifting (something I have done in NDs and want to duplicate in a LD) Although, now that I think about it, it was fun roaming around and shooting zombies. I am an avid airsofter\paintballer, and zombies is one of my favorite airsoft variants. So, I guess you’re right. I was just worried that it may have been a serious issue to regress after realizing I was dreaming. Thanks for the reassurance 
That has happened to me to, try doing a RC directly after you think you’re in a dream, because the mind is like on autopilot and you forget you are dreaming even if you think it and the mind change trains of tought very quickly. 
When I become lucid i don’t forget i have a false awakening. does anyone else have this?
That, by definition, is a lucid dream. You knew you where dreaming in the dream; the very difintion of lucidity. Sounds like it was a low level lucid dream though, in that you didn’t really comprehend what being lucid would enable you to do. Basically you knew you were dreaming on some level, but didn’t realize that you could do whatever you wanted because of that.
The way that works best for me to handle that problem is just to shout “Increase Lucidity Now”. Shouting this out emporwers you and helps you realize that you have control of the dream, thus increasing your “degree” of lucidity.
Yup…like Lucidity_Master said, you achieved lucidity…true, it was low lucidity, but still lucidity.
Don’t worry, your lucidity will improve in time.
Next time set your intention on rubbing your hand, touching the environment, or shouting: ‘‘Increase Lucidity!’’.
That’s pretty much all there is to it.