I created a sandbox Paypal account and made two separate purchases, while Google tag manager was in debug mode. In both cases the tag fired, but only one order showed up in Google analytics. The order I made first did not appear in Google Analytics, but the second one did. The reason I performed this test was because the site experienced a severe under reporting of transactions in analytics compared to the woocommerce data on the website. I also wanted to eliminate the possibility that the discrepancy could be caused by ad blockers or users that disabled js.
Does anyone know what can be the cause of this discrepancy?