v8.3.0
I just tried to delete 20 device connections from the gateway web portal by multi-selecting them using the "select all" checkbox (showing only 20 of 27 - this is important - devices on the page,) and it said it succeeded, but it didn't delete the devices selected. It seems to have deleted something looking at the recording below but unfortunately I didn't check the device count totals before and after.
When I changed the display count to be 200 to show all devices and did the same thing, it worked successfully.