Motion sensor activated, but not switching light on

I have a motion sensor trigger my hallway Light. 99% of the time it works brilliantly. Sometimes, you can walk past and it won’t come on. Sometimes you can walk past and it’ll switch on a good 5 secs after the fact.
The strange thing is, if you look at the activity within the smart app the sensor is picking up the motion every time, it’s just not switching the light on, which is very strange. Any idea what could be causing this? The particular brand of smart bulb?

Thanks

Possible cloud delay. What smartapps are you using? Brand of motion sensor and light?

I Was using the smart lighting app, but switched to smart rules to try and fix it.

It’s a ST Motion Sensor and the bulb is a Osram Smart Plus LED-Lamp White

Thanks.