The biggest problem is that managers can easily fall into a trap where they have everyone in the same place so they can ask individuals questions that only really matter to them. Beyond about 8 people (and maybe as low as 5) this means a bunch of people are standing around while other people give updates on things they don't really care about. I've seen standups with 20 people that last 45 minutes as the manager goes around the room, basically. That's not a standup.
It's even worse if PMs and other non-eng are there. Just, stop.
This brings me to my second point: size. Standups need to be small. No more than 4-5 people ideally. In an office environment these people should be in a pod of 4 desks (possibly minus the EM and/or TL who might have broader responsibilities) and they should be able to turn around and talk to each other, at which point you don't really need a standup anyway.
But I can't tell you how many times some EM has triggered crisis mode due to impending deadlines and we end up spending an hour a day with 20 people in a "standup" until the situation improves.