The 6 ohm load resistor in parallel with the LED is probably causing the voltage to drop too low. That LED bulb in parallel with the 6 ohm resistor probably results in a resistance of 5.4 ohms, ...

The Z201 device has a load-life stability of ±0.005% for 2,000 hours at 70°C, a resistance range of 10 ohms (Ω) to 100 kΩ, a power rating of 0.3 W at 125°C, current noise of less than -40 dB, and a ...

The CSM3637Z Bulk Metal Foil surface-mount, Power Metal Strip current-sensing resistor specifies a load-life stability of ±0.2% at +70°C for 2,000 hours at rated power.