Good idea making the GIF. Now I'm even more confused, though. If I had a dollar for every time I said "The code SHOULD work!" I would have one more dollar now. Everything in your TESR class matches mine, which works for the exact same version of Forge (184.108.40.2063).
Try looking at vanilla TESRs and copy-pasting their code? I doubt it will help, though.
I've got to go. Good luck!
This is me right now: