Thats sometimes happened on rice-made clones. I got Diga Tacho and it works same way. Sometimes works, sometimes not - depends on its mood. It works good with all 93Cxx, 24's and 95xxx memories. Some VW's and GM cars. But others not always.
Propably when you read dump from memory it damaged some bits and when you written it back with bad bits it works wrong way (usually problem is on reading mode - 8 or 16 bit mode). I'm usually saving memory dump in internal memory (in programmer) and then working on the dump. In case of bad luck I can restore previously saved dump to dash and got it working. Good luck!