Ok, so that didn't work, but I did find a workaround.

I just took the connection string from Minibits, entered it in the "Connection for Sending" field on Stacker News, then added my Minibits LN address as a receive option.

Couldn't get the string to work in their "Receive field, but since I can use the LN address as a different option for receiving zaps, it all works out.