Tom Kent wrote:

...

* Can't create libraries for bzip2 and zlib (showstopper? anyone else seeing this?)

I haven't seen your initial report of this issue (on the users list?) but it's probably caused by this change:

https://github.com/boostorg/build/commit/5ad92cd76ff393792f30aa50688c95eff24...

Or maybe not. This is in 1.69.0, so it can't be the cause.