I've learnt a few things recently about keeping SPS. I added some in July and for the first time ever, the majority are still alive, healthy and growing almost 4 months on.
If your water has genuinely got the ideal parameters, ensure you are dosing Amino Acids, Strontium and Potassium. I have been using the Ultimate Aquacare products and I have absolutely seen an observable improvement in the health and development of my Acro.
Turn your lights up. I have Maxspect Razor, I had them down lower to try to dissuade an algae from growing but the corals were not growing. The Acro faded as a result. I turned my lights onto a pre-programmed setting that ensures a strong and long light spectrum and everything is growing well.
Look at photos of the coral in the wild on the net and try to replicate a natural position in your tank. Maybe you have it angled oddly or something. You can angle the coral so it is pointed into the light so it receives the most cover without making shadow but it requires some observation.
Good luck!