Repro steps:
1) Open the project attached ReflProbes and test.scene in it
2) Notice the cube in the scene
3) Press Bake after selecting Reflection Probe object
4) Notice no cube is baked into the probe
5) Change Graphics API (OpenGL2 f.e.)
6) Bake the Probe and notice the cube is now visible

Workaround: Delete nolightmap parameter in the cube's shader

Reproduced in: 5.4.0b18
No repro: 5.3.4p6