Try adding in the receipt line number and see if you can see if it is skipping numbers? often times it will only print odds or evens. You may need to look at the visibility expression on the main area of the report.
This was the workaround response I received from Acumatica Support:
Hi Shane,
This current functionality insures that user can print inventory labels if they receive large amount of qty. For example, if user receive single item with 10,000 qty, it would not be convenient for them to print 10,000 labels.
If user wants to print multiple labels for single line item, please user line splits per qty to print multiple labels.
An idea can be created on community where system gives an option to user to select one label or multiple labels for printing. If this idea gets enough votes from the rest of the community, it may be possible that product team include this is future releases.
https://community.acumatica.com/topic/new
Please let me know if you have any questions.