Black Diamond Storm 400 headlamp question

I have a Black Diamond Storm 400 headlamp and cannot get the large center spotlight beam to produce a constant high brightness beam. If I turn the headlamp on with the spotlight beam selected, it turns on with high (possibly max?) brightness, but then drops to a very dim level after about 3 seconds.

Holding down the power button with the center spotlight beam illuminated causes the spotlight beam to alternate between a "bright" and "dim" setting and also toggles on/off the smaller flood light, however if I let go of the power button with the center spotlight beam in "high" mode, it returns to the "dim" mode after about 3 seconds, as described above.

Is it possible to cycle through a continuous range of brightnesses for the center spotlight and then have the headlamp hold and remember the last brightness setting selected? The last Black Diamond headlamp I had (a Spot model) was a much simpler (and older) headlamp but had no problem doing what I'm describing.

I've read the manual and product reviews but am not sure what I'm missing. I tried contacting Black Diamond but never heard back.

All other headlamp functions work as expected.