Typed Commands Not Working While Copied Commands Do

I am using a late 2015 iMac with mac OS 10.15.6 and Google Chrome to take the course. I have noticed that some commands, like “1s -1a” never work when I type them, but when I copy them from examples in the notebook to the shell they execute. It doesn’t seem to matter if I use the main keyboard or numeric keyboard keys to do entry. I’ve also had issues where it seems like files that I’ve created can’t be found by certain commands like “chmod” even though I can see the files are there. I’m wondering if the two issues might be related. Any ideas? Thanks.

@bayodesegun Can you take a look?

I’m sorry, I don’t understand. What do you want me to look at? I don’t see any links or text in your reply. Thanks.

@mstracks I asked a developer to take a look at your question.

I see. Thank you very much.