Well I have multiple bug reports for Guardian, I'm not sure if there are other posts about these but anyways:
1) Sky shield works inside the train where you plant the bomb on second objective from Trainyard, it fully stops airstrikes from hitting the train as well as nearby areas. Don't know if this is intended btw.
2) Sky shield drone seems to be thrown out of Guardian's feet. Everytime I try to throw it over a fence or a window it stucks on the border of my feet somehow and it's annoying.
3) Revive won't work on smoke.
4) If a teammate dies carrying the override core. Guardian can't revive them before taking the core apart from the fallen ally... This happened to me multiple times.