How to export cubemaps to Photoshop then back into Unreal

Hiya,
I created a Scene Probe that create a cubemap render target.
Now the problem I have is that if I right click the texture created and Export to Photoshop. Then open it and save as a TGA this file cannot be used as a cubemap in Unreal, the shader throws an error.
I think this is because internally Unreal actually has the cubemap as 6 square textures next to each other, however when it displays and exports they are in lat/long format. Apparently Unreal cannot import a cubmap in lat/long format but needs the 6 square files for all directions.

Any thoughts on how I can export from Unreal in a way that will be possible to be imported again.
I remember a tool that lets you convert between different formats but that was ages ago and now I cannot find it again.
Andreas