I have the same problem, with the same RGB board.
Everything with RGB is listed below
ASUS ROG Crosshair VIII Hero WI-FI 6 X570
2x8Gb Thermaltake TOUGHRAM RGB DDR4 4400MHz
1 RGB strip (not addressable)
Thermaltake View 37 Case aRGB Edition
ASUS aura never reads 27 leds and I don't want to remove the U1 chip, just a solution for this problem.
The trick to switch port and numer of leds to 27 works and also resets to 1 on power down/up.
I don't think I will ever buy a TT case again, very dissapointed.