I thought I would pass this tip along. I discovered this in trial and error.
I launched Logic X the other day and I had something like 15 plugins NOT passing validation. In addition, it crashed Logic (their AU validation tool still needs work). I launched the plugin manager and selected all the crashed ones and told it to Reset and Rescan Selection. Still, all or most failed. This time I selected one plugin that had failed and selected Reset and Rescan Selection and it passed! I tried it on the next one and the next one and guess what? They all passed and were re-validated!
So the next time you have issues with multiple plugins try to Reset and Rescan each one individually.