It’s likely just preventing you from typing something that would exceed reasonable limits. Inches/sec is very fast - 10ips is 254mm/sec. The camera alignment window won’t let you enter anything faster than 500mm/sec (19.69 in/sec) so if you try to add a 2 at the beginning here:
… that would make it 21.69 in/sec, which isn’t allowed, so it won’t let you type that. Select the whole thing and delete it, then type and you should be able to.
You said, “the only way I can get close is by zooming in a lot” - I was confirming that, yes, that’s required, regardless of camera. The system is fussy and needs you to be quite precise when setting it up in order to get good results. The camera must be rigidly mounted, and the mounting point must always be the same distance from the top of your material.
When you say, “the issue persists” - what issue? Show pictures? Remember, I can’t see what you see, so you have to spell it out.