Just adding into this thread, I found the same issue today on my 2014 L405 (53k miles) which is now sold and en route to a good friend so a concern. I tried everything on the display I could change but to no avail: fully functioning Satnav, route guidance, scale chaging etc...just simply with no map "underneath" the functionality buttons and display, exactly as per the first photo above. As with all things JLR (and Italian to be fair), magical off/on CTRL+ALT+DELETE was my first port of call but to no avail. Forensic reconstruction followed...
a) I'd dropped the car to access mode to load an eBay sourced spare wheel for the new L460 (cancelled order overhang and folk deciding not to tick that "option" who've evidently never used goo and a compressor).
b) I'd set off slowly across a private forecourt but the car was subsequently still held in access mode and the SatNav still set to the present destination.
c) I'd put the car back up to normal height manually to roll over forecourt speed restrictors and reprogrammed the SatNav with my return postcode while doing so.
d) While my wife may have temporarily recanted her point that men can't multi-task, it seems JLR didn't: the SatNav map never came up.
So after 70 miles back on Waze (much better anyway TBH but not the point here

) pressing buttons galore I double locked the car, re-entered with JLR's ingenious relay theft helper fob and with the SatNav on, I retraced my steps...dropped to access height, raised to normal, raised to off-road for fun, dropped back to normal, then turned the car and thus SatNav off and on. Like a rabbit out of the hat the map re-appeared but I've no real idea which of the previous steps (if any) did the trick.
I'm obviously not counting this as a success and will explain everything to the new owner while underwriting the fix under the adage of "never upset your Surgeon." I'll report back if it goes again with the new owner, or not if it doesn't. I did go back out an hour later to re-check before writing this and so fully expect the map to disappear again the second I do, but in the interest of community spirit (these forums are especially helpful to owners) I pressed the post button anyway.