Feature Layer Graphic hidden under tile layer

[BrendanMcCann]

Hi All,

I've an issue that when I view my map at a certain level of zoom my feature layer graphics appear below my base map tile layer, this seems to have changed between JS v3 and v4. Order of layers has no affect although changing base layer opacity can help. (see images for reference)

v3 

 v4

 

Any thoughts or solutions would be greatly appreciated.