Nothing really new to add to the discussion, but I could grow any plating montipora corals like weeds for years; until last year. Here's some information/thoughts from my experience.
First, some photos for reference...
Photo by ChristopherKriens
The green and red plating montipora colonies were both M. hodgsoni purchased from LiveAquaria's Diver's Den.
The corals grew very well under T5 and LED (Radion) lighting, but I found that to keep the bright red coloration under LEDs, I needed to supplement with two ATI Aqua Blue+ bulbs.
With a heavily stocked tank, my nutrient levels were always on the higher end; NO3 around 24-32ppm and PO4 was also high.
The corals grew differently depending on the amount/type of water flow. They do like high water flow and will grow towards it. The corals that were placed lower in the tank and not in a direct path of the water flow would grow down towards the undertow created by the water pumps.
I had great success with many other types of plating montipora corals in this tank; Idaho Grape, M. danae, M. undata, M. spongodes, Purple Rimmed and the Nauti Spiral.
All of them grew very fast and had great coloration.
Until...
Last summer, the montipora corals started to look drab. The coloration faded so that it looked like a silvery tone of the original color. After a few more weeks, the colonies started dying off. Nothing major had been changed/added to the system for months; maybe a year. I had implemented an ATS unit to help lower my nutrients which was maintaining them at better levels, but those were still high (NO3 at 16ppm).
To find out what was happening, we checked for pests (montipora eating nudis); found none.
I started fragging the decent corals and displacing them amongst other friends' tanks to see if they would survive and most of them did.
I decided to send in a water sample to be tested (TritonLab). The results showed elevated aluminum (two MarinePure blocks in sump) and extremely low potassium (should be 400, was 260).
In researching the potassium issue, I found that my salt mix (hw MarineMix) had bad batches of salt with low potassium. In trying to lower my nutrient levels with larger water changes, I was inadvertently driving my potassium levels lower with the bad salt. I ended up losing all of the montipora corals and the tank was eventually torn down; a new system is in progress.
To conclude, montipora corals are very hardy and should grow well and fast.
I'd take a look into the water parameters first. Montipora corals do well with higher nutrient levels and good lighting. If you're having issues, check your potassium levels; maybe the aluminum also.
Good luck.