Or so I thought... That test transfer has the status of "0/unconfirmed, not in memory pool" within Bitcoin Core. I have done some reading on this (other forum posts across the years) and I'm not clear on why is occurring
This means that the transaction has been rejected for some reason.
Depending on the fee rate used... it's possibly because of the "mempool min fee". But you should really have received an error message when attempting to send it... rather than it just showing as "not in memory pool".

You can attempt to rebroadcast it... right click the transaction, select "Copy Transaction ID":

Then goto the "console" in Bitcoin Core (Window -> Console):

Then enter the command:
getrawtransaction PUT_THE_TRANSACTION_ID_HERE
That should give you a big long string of random looking "hex" characters... 0-9A-F... copy paste that string and use the command:
sendrawtransaction PUT_THE_HEX_STRING_HERE
If it all goes well, you should receive the "TransactionID" as output...

However, if, instead of the TransactionID being returned, you get some other error message, post the error message here.