A while ago I got involved in a project with my current PhD supervisor that consisted on coding about 120 papers for a Meta-Analysis that took a considerable amount of time. Due to the fact that the paper was conditionally accepted, I was told that I would appear in the acknowledgements as a contributor. However, when the paper got finally published, there were no acknowledgements mentioning my name. I raised this issue to my supervisor by email and answered with "I did not realize" but did not even add an apology for the lack of recognition. What can I do to get recognition for my work?
I think you overestimate the value of being listed in the acknowledgements, which is not to say that an apology was not in order (but this is not worth pressing about). However, there are almost no tangible ways in which being listed in an acknowledgements section of a paper will help you professionally. The most it will do for you is that your name gets seen a couple of times, which may remind/inform a reader of your existence as a human being.
The ways that you get recognized for work which either does not get published or you do not get co-authorship are:
Appreciation by other researchers who personally know what you did (e.g., your professor). Consequently they may be more motivated to bring you in on projects in the future, which you might get coauthorship for or at least be in a good position to get a strong letter of recommendations.
(less direct) You gain experience and knowledge from this work, and it may be that you will have an opportunity to share your newfound wisdom with someone in the future, who may be impressed.