Since you have GVB Flex, all journeys by bus, tram and metro will be visible in MyGVB.
So if I don’t have any GVB flex, I would be able to see all the transactions on NS?
NS Flex normally consists of two products on your OV-chipcard: the one for train travel and the one for bus, tram and metro travel. In your case, you only have the train travel part of NS Flex, and you have GVB Flex taking care of the bus, tram and metro part.
If you were to remove GVB Flex from your card and get the bus, tram and metro part of NS Flex enabled on your card, then yes, you would be able to see all the journeys you make after that in Mijn NS. Journeys you already made will remain visible in MyGVB only.
Once you have removed GVB Flex from your card, you can contact NS customer service directly to have them enable the bus, tram and metro part of NS Flex. This change then needs to be confirmed at a ticket machine to take effect.
Contacting NS customer service directly can be done by phone; they are available 24/7 at 030-751 51 55. You may also contact them by chat (click the link Chat with NS on this page) or by sending a message on Twitter or Facebook. Note that it can take a few days to receive a reply if you contact them online.
Thank you for the detailed explanation!