It looks like you are doing everything you need to do to address the problem.
How long has it been since you changed the filters and DI resin last? I'm sure they are doing their job but was asking to see how long it's been since you have been using 0 TDS water.
I'd estimate that I ran my DI spent for roughly 2 months... during that time I was dumping 14 TDS water into my tank. Cyano and macro algae grew like crazy!
I've probably been running with 0 TDS the last month and the cyano and macro algae have decreased significantly but they are still there.
I'm being patient with it as I'm sure there was a large accumulation of nutrients during that time and the macro algae and cyano got a foothold in my system. Eventually, my system will revert to its normal balance and the cyano and macro algae will go away.
As long as you're seeing progress, I'd let it be and keep doing what you're doing. If not, perhaps look into shortening your light cycle or backing up on your whites channel and running more actinic? Any thoughts to the red LEDs in your fixture aiding in the macro growth?
I'd also manually pull as much as possible.
I can only lend to what I've experienced but I'll share what had worked for me for a SPS dominated system... oversized skimmer, GFO reactor, biopellet reactor, carbon, and CaRX. No water changes, no mechanical filtration (filter socks), and no vacuuming of the sand ever. Mileage may vary but it worked like a charm on my old 125-gallon and my 215-gallon. I even experimented a bit at the start of my 215-gallon and tried to remove pellets and also GFO but found the greatest success when I just repeated the same formula of my old tank.
Hope the input helps!