Ok, cool then, I was afraid of missing something regarding those settings during your video :)

There is something I don't understand in your settings.
If "Store all peak caches in alternate path" is checked, what's the point of using "alternate peak cache path for the following paths" ?

Indeed, that's a big one...
Is there any thread on the Reaper Forum related to this ?
IMO, the normal behavior should be to trim everything behind.