The westbound carriageway at the eastern end of the M3 has an unusual temporary speed limit through the roadworks, it's 55 instead of the 50 that you usually find in such circumstances. It wasn't just one or two rogue signs, they were all like that so clearly that was genuinely the limit. The Jazz did not display that speed limit at all, it just showed "---". Not sure whether that's an issue with the software being unable to read the signs (maybe it's only programmed to look for "likely" numbers and doesn't know what to do with unusual ones ?), or maybe the the display just can't show it.
It was interesting that many drivers didn't seem to believe the 55 signs, and stuck resolutely to 50 !