The 10X conjugation buffer and 10X modification buffer contain a high concentration of salt, which can precipitate out of solution and form crystals at room temperature, and especially when stored at 4 degrees. This is normal, and occurs frequently. There is nothing wrong with the buffers. You can heat the 10X solution to 40 degrees and vortex, to get all of the salt crystals back into solution. Then, you can use the buffer to make your 1X dilution.