Filter > 3d > Generate Normal Map not working suddenly

in CC 2017, cc says there are no current updates for it, generate normal map is not working.  I did it this morning, doing it for the 2nd time today, without changing any photoshop settings and having closed photoshop this morning and re-opening it just a few mins ago, suddenly generate normal map is not working.  it worked all the time in CC 2015 as well, i recently updated (a day ago) to CC 2017 photoshop.

so what happens is, i will have an 8-bit srgb 600x600px image, i will go to Filter > 3d > Generate Normal Map, I will see the spinning flower pedal wheel that Photoshop uses to show it's processing something, then i will see my 3D tab group, which is nested along with Layers, Channels, Paths, appear to have things appear in it such as "sphere" it all happens so fast that i can't tell what else appears, but it seems like a typical set of things that would appear in the 3D tab when in 3D mode... i believe the other things to be "default camera" or "default material" etc...

my image is black and white, it opens and i'm prompted for dot gain 2.2, i just blow through that dialog box and then once it is opened, i switch the Mode to RGB Color.

PS sorry, so what happens is, all that activity in the 3D tab goes away, so it's at it's default state of "Create new 3d..." the spinning flower pedal wheel goes away and i'm left looking at my black and white image.  history shows nothing other than opening the file, and nothing to undo

HELP!

thanks,

like i said, it worked 1 time this morning.  no other updates have been done to computer, my car, house or business establishment