Are you using 32 bit mode images?
You probably have the color mode set to 32-bit per channel, or other incompatible image mode...
You can save a copy of the image file, set the image mode to 16 or 8, then save as jpg format.
Have you tried to use Save for Web instead of Save as?
No. We're talking about images that I have created from start in Photoshop. Save to web is grayed out so I can't save to that. Changing the mode to 16 bit helps, but why would I suddenly not have this capability. I know I've always created in 32-bit. I've never touched that setting before.
If you're not using High Dynamic Range images, and are trying to create JPEG or PDF - you really should not be using 32 bit/channel images.
JPEG is 8 bit/channel only.
PDF only supports 8 and 16 bit/channel.
Very few formats support 32 bit/channel.
And the addressing mode (32 or 64 bit) of the application has nothing to do with that.
Thank you all for your help. I don't know how that setting ever got changed. I've never touched it before and just now noticed when creating a new project in Photoshop that the the default set it to 32 bit color mode. Now I know I need to be looking out for that.