How do I simulate menu button on Android 8? So far I've used the Assistant Menu on my Galaxy S7 as recommended in this question, but after a recent update the assistant menu no longer contains the old menu button.

The "long press" suggestions in the answers doesn't work for me either.
Same problem here.  Found an app called "Menu Button" in the play store which has solved my issue with an old app (Loot personal finance).  I have no association with this app.