Compatibility of glass is
Compatibility of glass is paramount in fusing. Who is the manufacturer of the murinni? is it cerified system 96? was your clear glass System 96? Are you absolutely sure there are not incompatibility fractures on the opalescent ones too?
Essentially, you need to give a lot more information on the products, the firing, the equipment, etc, to enable us to give answers that are likely to be helpful.