Make sure you highlight the tracks you want for the multi edit, click on the left where the fader is then hold the CTRL key and highlight the others then go to TOOLS> MULTICAMERA, make sure you ENABLE and CREATE in that list other wise you will not see the multi pips in the preview window.

Advice..... when you have lined up your edits save the project and then re-save with new name, you can then get back to the starting point as you cannot start again (undo will work so far)
Press the "T" (TAKE) button in the track when playing back so you can pick a new take if you have the wrong one.