What's wrong with the synchronization of two photographic lights? Sometimes both lights are on. Sometimes only one is on.

I suspect that the return speeds of the two lamps are different.

Are these two lamps the same brand and model?

Did you set the same output function when shooting?

Are the two lights flashing in the same way? Are all the flash receivers plugged in, or is only one plugged in and the other led by light?

Supplement:

In this case, there may be something wrong with the photosensitive receiver on the studio flash.

You turn on the flash receiver and plug it into another lamp that has never been triggered.

Let another light.

I've been in your situation. I have a lamp marked by me now. This lamp can't be lit, and I'm too lazy to repair it, so I always connect the lead flash to this lamp and ask it to turn off the light and lead other lamps.

I have decided that if this happens again, I will plug in another flasher (I have two flashers).

If you don't want to make it up, of course it's better to repair it.