3M Bedding and glazing compound not available...what now?

I've been trying to locate this stuff everywhere I know to look and just everyone that carries it is either out or almost out. I ordered 2 from NPD and they emailed me and only had one. What gives? Is 3M withdrawing this from the market? If that's the case what is an acceptable, PROVEN replacement with the same non-hardening qualities as 3M bedding compound? Don't say butyl, clear silicone or to skip the sealer entirely. Thanks.