I did not disable the RBF, you can see it here on the "Pay..." selection from the "Send tab:
My transaction doesn't show up on the "History tab". It only shows up on the "Send" tab.
Oh, I just remembered a contributing factor to my problem. When I tried to send the transaction a few days ago, I got this message:
I didn't want to pay the fee, so I copied the raw transaction using the Export->Copy to Clipboard option:
Then I pasted the exported raw transaction into a few transaction broadcasting locations to get it out on to the network.
So, the transaction HAS been sent (I can see it in mempool.space), but apparently, my Electrum doesn't know that? How can I convince it to refresh it's list of transactions in the transaction History tab from a node that has it in the mempool?