I've used the Chemseal products from Spruce with no problems, other than the usual sticky mess ones.
I think the key is simply to buy to the correct specification whoever the manufacturer is. From the PRC document -
Meets requirements of specifications AMS-S-8802 formerly MIL-S-8802,
We typically use type II, Class B, with the following number giving the working time in hours (usually 2).
Just buy to the specification, the Chemseal product meets the same spec.