I already have brought this topic after installing BiaB 2018:
A certain number of old and new demos were "missing", at least, the style picker was returning a "not found" screen when trying to load the demo.

Meanwhile, a patch seems to have solved the problem for the new Demos (ex _Airily)
but not for the older ones (ex -BomMed+ (Bomba Medium).

In fact, I have checked with my older version 2017 and found that all the relative demo songs are still there in BiaB 2018... Only there are not "linked" to the relevant style.
As an ex., the style Afro Folk 6/8 returns a "not found" when trying to load the demo song, although there is a demo corresponding (SalsaAfroCuban68_Folk_114 demo) to be found in the "songs picker" of BiaB 2018.

The next question is: how do I "link" style and demo? In former versions, I had the possibility to place a demo with exactly the same name as the style and it was done.. Only this has been a (wise) tidying up action in BiaB 2018...
Bernard