It seems in the context of your story the old adage that organizations reproduce software in their own architecture again rings true, with multilayered bureaucracy, lies and promises resulting in "client state".
When I tried to explain to him that I fixed the thing he claimed to have fixed, I heard him hesitantly say it wasn't the same bug. Not sure what he told his boss this time around the fix was for, but I was able to fully reproduce the bug with this fix.
If you can't reproduce a bug, you cannot in my opinion say that it is fixed. If you have to reproduce it via local debugging and changing a value, or hard coding a value, I think you're possibly close, but there's a chance it might not be the case!
If you can't reproduce a bug, you cannot in my opinion say that it is fixed. If you have to reproduce it via local debugging and changing a value, or hard coding a value, I think you're possibly close, but there's a chance it might not be the case!