@iomex I think I've identified the problem here... what the sceneryobjects claim I've made are signs to Diagram 880 to warn drivers of an upcoming speed camera and remind them of the speed limit (pg 126 in Chapter 3). These, as you point out, should have a blue background and white border. What I've actually made are co-located 670 and 879 signs, which (and I'll have to check because I made them over a year ago) I made to the dimensions given in Figure 14-20 of Chapter 3 (pg 125), which are positioned at the start of a speed-camera-monitored speed limit section.
@ross4122 RE Speed Camera Sign: That sign you've linked is to diagram 878 and I haven't made it, the closest being the rather small 879 lone camera symbol.
RE Shelters: I could find no examples of Insignia shelters with brackets anywhere other than my local ones, so I removed them.
@whistlehead wanted to be able to make unprototypical long ones and in theory you can use the shelters either way round. Of course I also made the advert boards only display outside as per the real thing, so that's somewhat of a mute-point.
The main thing I wanted to do with the signs was to convert them all to DDS, tweak textures where required and hopefully mostly resolve the map-breaking directional sign bug. I guess now I'm also making some new ones.