I saw in one of your videos, you have a n scale bachmann empire builder locomotive santafe 4-8-4 #3780.
The radius track that is included with the bachmann empire builder is 11.25" Radius Curved, and looks like the radius you are using.
I was never able to get it to run on the radius that they included with the engine, lol, kinda funny.
I don't even try to run either of my bachmann 4-8-4's on 11.25 radius track, guaranteed derail on the front pickup trucks eventually, and the tender gets yanked off the track by the engine too.
In my videos I only run on 19" radius curves with that engine.