Object Z scale jumps to 0 when I render

I’ve got a model phone, and I’ve added some extrusion to the letters and numbers to make them stand out. But any time I try to render it, the Z scale of every single letter jumps to 0, which means the extrusion disappears, and the render looks horrid. This persists even if I change the text to a mesh, or I specify the sale as 1 and then lock the scale. Issue persists even if I delete everything else. Also tried CTRL+A to set scale 1. Still flattens upon render. Happens in cycles or blender render.

If I create new text it doesn’t have the problem, but replacing all 22 labels is going to be a pain, and I’d like a quicker fix if this happens again.

Can anyone tell me why this is happening?

File with just two sample objects: Phone 10 - key test.blend (656 KB)

You have keyframed the Z scale. 3D view properties -> transform: scale, right click on the Z field and delete single keyframe and change the scale to 1.

Thank you!