@jasoncoon, the current FastLED library uses bit-banging for driving LEDs so as long as interrupts are disabled, the 50us IR receive timer interrupt risks being affected.
One option is to use the Neopixel library which doesn’t seem to block interrupts. However, I am not sure how the IR receive timer interrupt will affect its operation. Another, is a DMA-based APA102 library from @Pixelmatix which works with FastLED. You’ll need to locally compile to get it working. 