Please read: Please read: make it easier to help you.
Particularly about formatting your code with triple-backticks, and providing a minimum working example (e.g., what is QP?). Also provide the full error.
The likely culprit is that x[i,j] * QP[i] / 3600 / 24 is too small for Couenne’s numerical precision.
Does the error go away if you make the lower bounds a lot larger (e.g., >= 0.1)?
You could also think about rescaling the problem. For example, you could multiple the objective by 10_000 to get some nicer numbers.