Procedural Foliage Spawner only spawning one element

Just wondering if anyone who has encountered this, worked out what what wrong? My files in a colleagues computer, or ones created from scratch is only spawning on foliage type, which has been correctly set up, and referenced in the spawner being used by the volume are only spawning one layer. We can change that layer to anything and it works, but we can’t have more than one spawning element in the spawner no matter what we tried.

To reiterate:

We tried creating new foliage type files and new spawner files and set that in the Procedural Foliage Volume details.
We copied files that work on my computer to his, but they did they same as above.
Foliage types have valid landscape layers, and meshes set.
To avoid any confusion, the Procedural Foliage has been selected in engine experimental.
Multiple collision values have been used.
Copying the one working foliage type and reassigning the static mesh does not make any difference either. Yes, we made sure new file names were properly assigned too.

Any insight would be helpful.