There is a circuit diagram simulation error. I don't know why. The first time I used simulation software, I uploaded the file. I hope my friend can help me have a look. The optocoupling uses 4N35, and I use PC817C instead.
The emitter of the photocoupler is not connected anywhere to allow a dc path. I once had a simulator with an unwanted result of an operating point, so I blamed the simulator and forced the operation point. once the bipolar chip was fabricated the chip ended into the operation point that the simulator had predicted.