To be precise, this is FSX Acceleration that I am using.
All of my scenery, original and many, many add-ons are in place in the correct directories.
All of my scenery functions perfectly except that which is driven by the bgl files in this directory:
C:\Program Files (x86)\Microsoft Games\Microsoft Flight Simulator X\Addon Scenery\scenery
When any files are added to or removed from that directory, FSX is supposed to pole the directory and register what is there. Now, following any change in that directory, it appears to be ignored by FSX and FSX at this point recognizes nothing in that directory.
All my regular scenery, both default and add-on scenery, works fine. Files in the noted directory do not.
The add-on directory contains over 200 sub-directories and they all work. The problem directory contains over 100 of which all used to work. They're still there but they go unrecognized by FSX.
And yes, the scenery.cfg is intact.
PS I've been at this for more than a decade and it's the first time I have had this issue.