Has anyone ever seen someone successfully receive a waiver to reenlist after getting an RE 4 Honorable Medical Discharge?

Not likely.
Even were you to find a doctor who agrees that you no longer have the medical condition, that opinion wouldn't change the Re Code 4. Re code 4 means you had a nonwaiverable disqualification.
Re codes aren't changed to permit reenlistment.
Waivers for medical disqualifications require your MEB proceedings, PEB proceedings, and evidence that the condition no longer exists or justification for a waiver.
See AR 601-210, DoDI 6130.03.

Never seen it happen. Most RE4's are not waiverable and they won't let you back in. But there is still a small chance and it is going to take a lot of legwork by you to get it done. If I were you I would talk with a recruiter and ask them what you need to do.

My wife has diabetes. She food shops monthly. She brings home bags of candy. I try to find the receipt to return them. If I can't I give the candy away.
She always denies that she has Type II diabetes, "Because she knows better." She has no outward physical appearance that indicate her diabetes - not fat, not thin BUT she does have confusion, vertigo, headaches and overall body pain until she eats something.
The other day she came across an old Reader's Digest (at the Doctors office) and said "Maybe the doctors are correct (20 years later) after all. When I asked her how that could be? She said she 'trusts Reader Digest'. She's had 6 different Doctors over the course of those years.
People believe people they believe. Maybe they aren't lying but you are in an extended denial.