I don't know the details of your application (no photos), but FWIW, I've used Sikaflex 221 in numerous applications, and all of them were successful.
I put it on our Interstate's roof in lieu of the previously-applied self-leveling stuff that aged out of effectiveness (details here
Not wanting to waste the residual contents of a caulk tube, I also used the same product on our house, to seal the exterior brick penetration where the air conditioning condenser lines ran up to the rest of the components in the attic. Those kinds of penetrations are notorious for being rodent superhighways. The Sikaflex performed wonderfully in that application, too.
It's tricky to apply and different people develop their own methods. I discuss that in the link above.