Sorry for the delay. Yes, I attempted what you have suggested. I also attempted many other combinations of things that I thought should have worked.
What finally worked is that I re-installed the software on the MicroSD card. After multiple re-installations to replicate and verify the issue, I think I have figured out what went wrong.
I am using the OSMC installer EXE for Windows. Apparently, when you misspell the WiFi password in the installation process (on your Windows machine), OSMC can’t recover from this mistake and you will never be able to get the WiFi to work, even if you re-enter the right password in OSMC when trying to connect to the network. I am not sure of the exact mechanics of why, I have only verified as best I can that this is the initial cause of the issue and it cannot be overcome later.