Hey @Tgbnamish
We have run thorough checks around quest variables and they show that you just started the quest, and the rest of the missing variables show that you never had completed the quest, if there was a case of faulty variables at all. I have also checked all possibilities of the mega stones being lost someplace else, like being held by pokemon you own.
Hence, it is clear that you never had the quest done. I'd urge you to follow through with the quest to attain the said mega stones, here's a Guide for you to check out.
As for now, I'll be keeping this thread open to any further replies if you happen to have something you wanna say or are in need of any help regarding the quest here on out.
Have a great weekend,
Fusionflair