Line shapes are disappearing against a coloured background

[defaultffcoraje9a1s]

I made a white line shape in the indesign document and when I created a navy background the white shape doesn't show up on the page (you can see it off the page) even though the shape is arranged to the front and the shape is set to 100% opacity on an RGB transparency blend space. I also set the navy background shape on a master page and the same thing happens.

The same happens to other colours, but this time the pink colour seems to be faded. However, if the shape is black it shows up fine. 

Anyone know what's happening here? I've never had this happen before!

[defaultffcoraje9a1s · Accepted solution]

Okay so I've figured it out! but will leave this post up incase anyone else encounters the problem:

It was because my lines were grouped! When the lines are ungrouped, the opacity layer style of the lines were set to "multiply" instead of "normal", when set back to normal the lines reappeared!