First this look like some bad interaction with OS that can't be fix from our end. I would need have exactly same machine recreate this bug to even try fix it.
Second your answer are not precise enough to see what you do, best if you describe what you do in steps what you do to recreate this bug.
E.g.:
1) boot machine
2) log in
3) run game
4) load save
5) map work
6) close game
7) log out
8) log in
9) run game
10) load save
11) have black map
Sorry if I wasn't clear. O.k., this is how it goes:
1. Compiled OXCE using the exact commands for Linux installation in Meridian's post. Did it last night on my Raspberry Pi 3 B+ board. Took about 2 (?) hrs to complete without any errors.
2. Played the game this morning --everything seems to worked fine.
3. Later in the morning, I reboot into my RPi3 B+ board & logged in and attempted to start my saved Battlescape game. It turned out that all saved battlescape games are affected.
4. The sequence went like this:
a) Boot into RPi3 B+.
b) Logged in Raspberey Pi Os (based on Debian).
c) Started OXCE in the terminal.
d) Clicked on the saved Battlescape game.
e) Game opened to black map screen with just my units & AI visible --same as the two images
in my first post above. All saved Battlescape games are affected.
f) Quit the Battlescape mission.
g) Clicked on the saved Geoscape game.
h) Game worked fine. I have one such save game where the skyranger was just about to land
on a terror mission.
i) Clicked on the saved Geoscape game with skyranger on way to terror mission.
j) Game opened to normal map, did the first turn.
k) Saved the Battlescape game and quit.
l) Clicked on the save Battlescape game, game opened to the same black map.
It work fine if I goes through the terror mission from start to finish, return to Geoscape & save it. But I do not have the time to play continuously, hence the need to save the game.
Regards,
Heybeardy.