Lightmap Shadows Not Showing on iOS Device

Hello,

As the title suggests, I have an issue with lightmapped shadows on the device. Specifically, the lighting seems correct however, the baked shadows are not visible.

A point to note is that, when include specific scenes in the Editor Build Settings, the shadows are visible on the device. When I disable these scenes from the build (which I need to do, since they are included in separate asset bundles) the shadows don't show up.

This is using Unity Cloud Build, for which I have different versions of Unity 2019. I need to use 2019 in the UCB since this is the version my project files are currently using - and no plans to upgrate, yet.

Anyone able to suggest why this might be happening?