What determines whether a stratagem will stick to an enemy or bounce off?

[(☞ ͡° ͜ʖ ͡°)☞]

?

[Botji]

Afaik on the bugs the armor tend to bounce them but stick if you hit the fleshy bits.
Automatons are a bit weird though and I have seen stuff stick on heavy armor bots(and the tank ofc) so maybe things only stick on "flat" armored surfaces?

[Forblaze]

Even when it sticks, it doesn't seem like it tracks properly either.

[「SHAORUNE」]

red stratagem will drop where the orb originally landed, even if it stick to an enemy. Only blue stratagem will drop wherever the orb is.