This is likely expected, given that there is not enough weight on the craft to warrant using all engines. If it can fly without them, that gives them a great idea as to how much payload it can take up when they are lit.
Edit: I may be wrong, apparently they have a great telemetry integration with their stream to show which engines are lit and which are not.
Yes. With 33 engines of a new design losing 1 or 2 would be pretty unremarkable and worth adding to the graphic. Losing 5 is getting into "needs improvement" and I'm sure SpaceX will be looking hard at the data they collected to see what about the design or ignition sequence they can improve next time.
Edit: I may be wrong, apparently they have a great telemetry integration with their stream to show which engines are lit and which are not.