I have had so very many lucid dreams like the one you described and I can tell you that I still get them alongside some quite vivid ones. All I can tell you is that your brain won't always be cooperative... I've had dreams where I did reality checks with numbers and they didn't change 3 times in a row, leaving me in a non-lucid state during a nightmare!

It's a shame when such things happen but you'll devise your own techniques to keep the clarity. Remember, at least you attained lucidity at all which is a great step and things can only go up from here.

I suggest you try swirling around in the dream that can help, or rub your hands together. Sometimes visualizing something you wish for within your mind's eye confidently can lead to what you want, just like visualizing light when you're in a dark dream like you were. Just saying something rarely works for me, you need to truly imagine it already being there.

It all sounds so difficult and can be quite difficult but you'll get there.

Experiment and don't ever give up...