With the latest build, when I’m compiling my Scrivener file into .mobi, I get this warning:

Warning(prcgen):W30009: Epub navigation file does not follow the specification. Please refer to Kindle Publishing Guidelines about usage of EPUB3 Navigation support. Tag should have value in file: C:\Users\User\AppData\Local\Temp\mbp_7E4_B_2_2_20_3B_296_3F38_383C_1\OPS\contents.xhtml line: 10 Warning(prcgen):W30015: Epub navigation file could not be built. Falling back to NCX based TOC Generation building.

As far as I can tell, this is creating an NCX file as an index, but not a separate Contents page, as it used to. Nothing else has changed on my set-up since the last version of Scrivener was being used.