I tried Luyren's suggestion to clean out the cache, but to no avail.
After the clean, I Immediately did a Windows compile which didn't change anything.
I then re-compiled with the Flash player and it works perfectly,
with the Aliens fading in and out, and Luyren's particles going off every few seconds as I programmed it to do,
but the Windows (and Android) compiles run the game but without these 2 features at all.
Given no one else has this issue, it must be something local on my Windows 10 laptop.
I don't think I have a virus because I have Norton's running in the background and it has never let me down for last 10 years.
Thanks for your responses - really appreciated.