the missing autocomplete experience, might be due to the folder location changes of the newer notepad++ releases, causing the installer not to automatically select the autocompletion option when updating.
(the old folder location was Notepad++\plugins\APIs, and the new folder location is Notepad++\autoCompletion\)
the usual fix is to install notepad++ again, on top of your existing notepad++, and make sure that autocompletion is activated at the installer.
(recommended version: 7.6.6)
here are some details from a similar issue:
please check if C:\Program Files (x86)\Notepad++\autoCompletion\xml.xml exists. (folder location example of a default 32 bit install)
if it does not exist, please download the 7.6.6. 32 bit installer from >>> here <<< ,
or the 7.6.6. 64 bit installer from >>> here <<< ,
and re-install it on top of your existing notepad++.
important note: make sure that auto-completion files is selected when re-installing.
if it does exist, please go to settings > preferences > auto-completion and check that function and word completion and function parameters hint on input are activated, as seen at the screenshot below:
best regards.