Particles disappear when cam close / low fov.Question

Hi everyone. I have a bit of an out-of-nowhere problem that my particle system suddenly isn’t visible anymore ingame.
To make it visible I can set the camera to perspective and move it further, or increase the FOV.
Obviously not ideal in a orthographic game.
Anyone happen to know what the problem is? https://drive.google.com/file/d/0B5oIJYQz9fpFdkU1OE96elZNSlk/view?usp=sharing
They aren’t being obscured by anything, so it’s not a renderorder issue. I tried removing everything that is behind / in front, to no avail. It’s not the clipping plane. And the oddest is, it worked two weeks ago, and all I changed is the Ui in another scene. (not loaded in here)

set the simulation space of the emitter to world fixes it. Definitely odd.