Yeelight filament bulb YLDP12YL problem

I have a problem with Yeelight filament bulb YLDP12YL. When I turn on the light, the bulb just pulses for a long time (looks like four less bright and one brighter pulse), then after some time lights up normally. But I cannot connect it to the app. I’ve tried to reset it (turning on/off five times), still does the same. I also set up miio_default hotspot, but the bulb doesn’t connect to it. Any help?