iPad: You can use the Apple Lightning to USB Camera Adapter and a USB cable to connect your iPad directly to your JD-Xi. If you do this, you will see "JD-Xi" as an option in the MIDI Ins and Outs in Patch Base. To work, you must also make sure that the JD-Xi is using the "Generic" USB driver.
Mac: You can use either the "Generic" or "Vender" setting on the JD-Xi. But if using "Vender" you must make sure you've downloaded and installed the driver from Roland.
To do change the USB driver setting on your JD-Xi (taken from the JD-Xi manual):
Use the Cursor [<] [>] buttons to select “SYSTEM,” and press the [Enter] button. The setting screen appears.
Select “USB Drv” and use the Value [-] [+] buttons to change the setting to GENERIC.
Press the [Exit] button several times to return to the top screen. The edited parameter is saved when you exit the system setting screen.
Turn the power of the JD-Xi off, then on again. After changing the “USB Drv” setting and saving it, you must turn the power off, then on again in order to get the system to operate correctly.
The Patch Base editor only fetches and allows editing for a small subset of the JD-Xi's System settings, due to MIDI limitations on the JD-Xi that don't allow for more full editing.
Patch Base manages the data in the JD-Xi in a slightly different (but hopefully more flexible) way than the menus on the JD-Xi itself do.
A Program on the JD-Xi is essentially like a "Performance" on an older synth: the Program stores your Effects settings, as well as pointers to which Digital, Analog, and Drum parts will be loaded from the JD-Xi's memory. So, when you save a Performance, you're only storing these settings. You're not storing copies of the actual Digital, Analog, and Drum parts as well.
In the Parts editors of the Program editor, when you select a Part, you're just telling the JD-Xi to load the sound that is stored in that memory location. The names you see in the dropdowns for selecting parts in Patch Base are based off of the latest data you loaded in the Bank editors of Patch Base. So if you haven't fetched the banks from the JD-Xi, those names won't be correct in the dropdowns.
Please note that sequences are not saved as part of Programs in Patch Base. The JD-Xi does not offer a way to fetch and store sequence data.