You are using the Netskope DLP solution.

There are two possible scenarios that would cause the behavior of files containing test data for credit cards not triggering DLP events when uploaded to Dropbox. One scenario is that the DLP rule has the severity threshold set to a value higher than the number of occurrences. This means that the rule will only trigger an event if the number of matches for the sensitive data exceeds the specified threshold. For example, if the rule has a severity threshold of 10 and the file contains only 5 credit card numbers, then no event will be generated. To fix this, you can lower the severity threshold or remove it altogether. The other scenario is that the credit card numbers in your test data are invalid 16-digit numbers. This means that the numbers do not pass the Luhn algorithm check, which is a validation method used by Netskope DLP to detect valid credit card numbers. For example, if the number is 1234-5678-9012-3456, then it is not a valid credit card number and will not be detected by Netskope DLP. To fix this, you can use valid test credit card numbers that pass the Luhn algorithm check. The other options are not valid scenarios for this behavior. The Netskope client is not steering Dropbox traffic is not a valid scenario because there are corresponding page events, which means that the traffic is being steered to Netskope. There is no API protection configured for Dropbox is not a valid scenario because API protection is not required for DLP detection on file uploads, which are handled by real-time protection. References: DLP Rule Settings1, Credit Card Number Detection2