It happened to me again and I was able to see a strange pattern: It seems to be related to the Cataphract. Not only did it happen to me both times on this mech, but from what I heard from another lance mate, he too was piloting one whe he had this issue.
The strange thing, though, was that it was not over after the first match. I played a second match with no map at all, on my Atlas, and then, on the third, it went back to normal.