My gateway doesn't appear in the Gateways tab on the Machines page.
Check that you have gateways by going to Data > Gateways and ensuring that the top right search field is empty.
The gateway will not appear on this page if it has been shared with you with User permission. In that case you should ask the gateway owner or admin to check that the gateway has been shared with you.
Ask the owner or admin of the gateway to share it with you by going to the gateway page, select the gateway and clicking on the Share button.
Then entering and selecting your name from the input field and clicking on the save button.
Once the gateway has been shared, refresh the page and clear its cache.