Search functin not working in Productions

Hi,

I have a production made up of a few Projects (TVC 1, TVC 2 etc) then there are my Master Projects inside the Production that have my assets ie FOOTAGE, AUDIO, GRAPHICS/RENDERS...

When inside the FOOTAGE Project I can't use the search bar to find any media. 

I can input the file name, but nothing happens after this point.

I have tried the search bar in all the other Projects inside the Production and it works perfectly fine, so my only conclusion would be the size of the FOOTAGE Project file? As its got the most amount of assets within it?

Any help would be greatly appreciated.

Many thanks
Mat