That reminds me that the great bassist Tal Winkenfeld, who played years with Jeff Beck, was enthusiastic about four songs which were started with Brian, Jeff and other musicians, among them Tal. Nothing ever surfaced.

I think that was probably much more on Brian’s side as far as the decision to not use the Beck tracks. The 2013 tour with Beck was rocky, and subsequently Beck said some unflattering things about Brian in an interview or two. They may well have had mixed feelings about using the material prior to Beck’s comments, but I think once he made those comments, it was not surprising the tracks were dropped. It was unclear how finished they were in the first place.
Pairing Beck with Brian was always weird (both on tour, even with mostly separate sets, as well as pairing them in the studio), and Beck talking s**t after working with Brian was uncool (to put it very politely). As those who follow both Beck’s career and his other collaborations, this one with Brian was not the first to go south and end up unreleased.
Having said all of that, I can’t deny that I definitely want to hear these tracks. I mean, they *could* be really interesting.