Based on how I read your posts, my understanding of Intellisense is that your expectation of when you'd see pop-ups exceeds when pop-ups are meant to occur, considering how Microsoft built the Intellisense feature into Excel.
For example, regardless of any settings, I would not expect to see the pop-up based on your scenario with this you wrote:
"When pressing enter after the first line, and typing "s" to get the "Selection" of the second line, Intellisense does not pop up."
In this regard, Intellisense is Intellisense, it is not Intelli-mind-reading. Neither Excel nor VBA would have any way of knowing that the word "Selection" is the word you plan to invoke by hitting the "s" key. That next word might be "Sheets" or "Sort" or "Subtotals" or "SpecialCells" given the "s".
The key issue here is context. Intellisense depends on the context of the code and displays all possible completions for input. Because you hit the Enter key to start a new code line, there is no context for Intellisense to recognize, even by typing in the letter "s", until a complete object name is entered, then a period, to set the code context Intellisense requires.