That's a rarity. But non-responders to Sema are not unknown.
It can be because you have a genetic mutation that causes an abundance of GLP receptors, which results in a kind of insensitivity. The overall sensitivity to appetite suppression of Sema has been theorized to be dependent on the overall proportion of receptors agonized.
Women, for instance, in general have a lower density of GLP receptors than. men, and generally respond better to a lower dose.
There's a $300 genetic test that can predict this, along with other factors related to likely success with GLPs,
Sounds like GIP did the trick.
The other possibility is the natural presence of anti-Sema antibodies. Something seen with users of earlier incretin drugs. Ever injected anything else for diabetes?