The appropriateness of this situation depends vastly on:
- Purpose of the meeting
- General patterns of working with that professor
In this case, there's really only one piece of information given to go on, and it's one that actually backs up the professor's behavior (mostly): "a meeting put on by the group that funds the project." This is basically an issue of rhetorical goals: what is the purpose of this presentation? If you're a PI presenting to sponsors, this is a money meeting. Yes, it is a research meeting (research results are presented) but fundamentally the relationship is that some group gave the PI's money to do something, those PI's were responsible for it getting done, and the PI's need to show something got done. If you did it well, they're still responsible to the sponsors. If you did it poorly so it never got done, they're responsible for that too. Either way, to the sponsors, the outcomes rest on the PI's. Even from your perspective, the best outcome of this meeting is that your PI shows the sponsors something good, the sponsors find more money, and it supports you (or people like you) for more good research.
At least in my field (and almost any that I can think of), presenting in a closed meeting to sponsors is typically not considered something you'd list on a CV (it's below-board), so authorship credit is somewhat of a moot point. There are a couple of exceptions to this. First, if you were a PhD student or postdoc, the PI might want to list you explicitly or highlight you to help raise your profile with those sponsors when you submit for grants in the near future. Since you're an MS student, you're probably a ways off from that, so there's not a ton of sense promoting you to sponsors (who might well have changed jobs or retired by the time you had a PhD). In fact, as a master's student, I would say that even being brought to a sponsor meeting is a good sign (e.g., you're getting networking with sponsors and other labs). So I wouldn't feel so bad. Flip it around: what would you have hoped to gain from being highlighted in that presentation? You're there at the meeting, you can just talk to people about what parts you did.
On the converse though, I would say that burying you at the end of the acknowledgements is a pretty thankless treatment for a major contributor. I'd never do it, and most people I know would never do that sort of thing intentionally. So I would be on the lookout for if this pattern of behavior ever touches an actual publication or presentation in an academic venue (e.g., conference, workshop). Leaving authors off in that venue or burying the main contributor in that context is a serious no-no. So that's where the pattern issue comes in.
But keep in mind that sponsor meetings, open academic presentations, and invited talks are really all different animals that serve different purposes (e.g., respectively: funding, reputation/ideas, depends on the invitation!). Credit and responsibility are not the same across these, because in each case you are trying to accomplish different goals when you speak.