The simple answer is “Yes.” The priest may just have forgotten to lead the community in the prayer or may have a good pastoral reason for omitting it (e.g., a baptism during Mass, time constraints, etc.)
Could I also gently challenge the questioner? Where do these “does it count” questions come from? What spirit elicits in us this need or desire to worry about what “counts”? For some, Mass devolves into doing the bare minimum: “Does Mass “count” if I’m there from offertory to communion?” And those who leave before the final blessing make me wonder why they come at all, although again, maybe someone has a real need to leave immediately after communion: e.g., a sick child or elderly parent who needs assistance. I just can’t believe one could always have that urgent a need to bolt early.
I would suggest we not worry too much about what “counts” and focus more on the loving worship and celebration the Eucharist really is. At Mass we receive the gift of God’s very being (that’s why Catholics “receive,” not “take,” communion). Any and all of it is wonderful and transformative. When we think of Eucharist this way, we are way beyond worrying about what “counts.”