Keyframe not working when exporting

Hi! Not sure if this is the solution here (also a bit late, but it might be useful for someone), but I see you're running Media Encoder in another language. In your expression, if you set 

effect("Slider Control")("Slider").value.toFixed(1)+"% Energy"

to 

effect("Slider Control")(1).value.toFixed(1)+"% Energy"

it might work.

If it doesn't, you might have to additionally rename "Slider Control" to something else than the default name, because AE will rename it to the used language's name.

That's strange! I set up a similar project on my end and tested. Seems to be working fine. Is your Media Encoder updated? Have you tried exporting it anyway? Just to be sure that it's not just the preview in Media Encoder that's messed up. Also, what happens if you export from the After Effects Render Queue? Do you get the issue? If nothing helps, please share the project file for testing. Feel free to share it via DM if you prefer not to share it publicly.

Let me know.