Teresa
You are correct that if the images do not seem to overlap based on initial configuration, the block adjustment won't run.
It's hard to know what might be wrong without more discussion, but this diagram shows the different parameters that affect how large the images will appear on the ground.
Ortho Mapping assumes your drone altitude values reference sea level (geoid, blue) then calculates H, but if you're not near the coast and your drone reports H, the apparent footprint will be tiny. It's also possible that your focal length or sensor size are wrong but that is unlikely...
Did you change your Elevation Source?
If you try again and it does not work, could you upload one raw image here? I'll look at your image metadata. What drone & camera are you using?
Cody B.