My objects fade out when I increment the opacity of my background image This is kind of strange. Whenever I increase the opacity of my background image, the opacity of the other objects surprisingly decrease. This is such a pain, and since I'm fairly new to Blender I can't seem to solve it.

I've looked for a solution on Google before asking, but couldn't come with anything handy.

Any ideas? Thanks.

PD: It's like if the background image were on top of my other objects. But I can't seem to find a way to change the placement between objects and background image (if this makes any sense at all).
The Setup you're currently using is quite common in modelling, as you usually want to compare a blueprint or sketch to your model and trace some elements of that. A feasible value for the Opacity would be around 0.3, so you can see your model more clearly, but still compare to your underlay.
If you want the underlay to really be behind the model you're creating, set the Toggle Switch just below the Opacity slider to 'Back'. See comparison screenshots below:
Front

Back