Using multiple MATLAB level 2 S-functions in one Simulink model?

I have a model where I have simulated the response of drone using an S-function. I am trying create a simulation where I have multiple drones simulated in one Simulink model, but the response is not as expected; somehow if I put two or more S-functions in, all of them behave unexpectedly. Uncommenting all but one S-function will produce the right response for the specific S-function.

I am using MATLAB Level 2 S-functions. I am wondering if the S-functions are sharing variables, or if anyone else has experienced something similar when using S-functions.

Reading some documentation, I was under the impression that this is not a complex task, so I am wondering where specifically I should look for what could be causing this issue. Is using multiple functions something that needs to be declared explicitly in the s-function?