Fluid: Black bars on the side of the screen or desktop not fill iPad Pro 11" screen

When connecting using Fluid Remote Desktop, Jump Desktop tries it's best to switch the resolution of the remote computer to match the aspect ratio of the device you're connecting from. If Jump can't find a resolution with the exact aspect ratio, you may see black bars on the on the sides of the remote screen as Jump will fallback to using the closest aspect ratio it can find.

You may want to try and manually find a resolution to connect at by trying to switch the remote resolution while connected to see what looks best and then set Jump to use that resolution (right click your connection icon -> Edit -> Displays -> Custom Resolution). On a Windows machine use 'Display Properties' to switch between resolutions or on a Mac, use a tool like QuickRes.