IF you were working, then you are most likely legally entitled to a lunch break if your local laws require one. However, there is a huge difference between legally entitled to and what the company culture permits.
For instance, many companies do Lunch and Learn events and try to pretend that it is your lunch break but it is really a training session that should be considered paid work time not an unpaid lunch time. However, in the company culture, they expect you not to consider it as work time. You can take a real lunch break after but be prepared for lots of push back from your colleagues and your boss especially if you your charge your time to specific projects or clients as taking a lunch break and calling training time work will mess up their percentages of productive time.
An actual lunchtime meeting with colleagues from other departments who don't sit by you is easier to get by with taking your real lunch afterwards (or earlier) because no one will notice. Personally I always take a lunch break away from the office and my coworkers are used to that. So no one questions when I do the same after a meeting that happened to be scheduled at lunch. Many of my coworkers work at their desks and eat lunch there or skip lunch entirely. Most of them are the ones who schedule lunchtime meetings.
It helps to block your lunch period off on your calendar and then fewer of those meetings will be scheduled. I usually push back on meetings scheduled at lunch unless I know they are something time-critical or the organizer is having trouble scheduling.
A big deal meeting with a fancy catered lunch and senior management is usually going to be considered as your lunch break in most companies I have worked for. Nor can you usually ask for those types of meetings to be rescheduled. If the CEO wants a company-wide meeting at noon, then that is what is going to happen. Sometimes, it is in your best interest to just accept that. Luckily these tend to happen relatively rarely.