In 7.2, AutoInput does not work if text is entered into a cell beneath an empty cell. This worked in 7.0, however.
Also, with no empty cell above, autocomplete seems to start becoming active only when the string entered is unique. I seem to remember that in 7.0 (which I have now replaced with 7.2), autocomplete started after the first couple of characters, giving you a choice (with the Up and Down Arrows) if more than one string matced, and so you could select the correct entry.
If somebody checks with 7.0 and confirms that this is a bug, not a feature, I’ll file a bug report.
Version: 220.127.116.11 / LibreOffice Community
Build ID: 9a9c6381e3f7a62afc1329bd359cc48accb6435b
CPU threads: 4; OS: Mac OS X 10.14.6; UI render: default; VCL: osx
Locale: en-GB (en_GB.UTF-8); UI: en-US