" If somebody's able to provide the exact steps for what they did to consistently reproduce the issue, that would be most helpful."
Sure, that would help, but it should be those who knows the system, the logic, also knows the best questions. I can explain 1000 circumstances surrounding why GSX replied the way it did, but Umberto knows the exact logic that surrounds that message and can then take the initiative for gathering leading info.
" it's happened before where somebody reported a problem with an add-on, and somewhere somehow, the issue was caused by another add-on that they were using. "
I recognize that definitely. But...
E.g. I have a new PC I9-13900 RTX 4090 with everything just installed. Still MSFS crashes (not this issue). So I thought maybe it's about other AddOns. So I removed 214 of 215 Addons, spent 2 days on test-scenarios, and it made no change. You know, this consumes a LOT OF TIME and I make zero money from it. If I though had a log that could capture the error and send it to Asobo probably it would be solved pretty soon.
Software producers these days sell beta versions and let the customers do the bloody test job they should have done in a early stage. Why, because you (well maybe you're a paid tester) and me and others works for free.
"So....what add-ons were you using, what airplanes, airports, what exactly were you doing when all this happened. As I said earlier, the more information, the better."
And as I wrote, the first step should be the support as they know e.g. if an Add on AT ALL could effect the issue, It's not the customers job to write paragraphs of smart potential circumstances to an issue they have zero deep knowledge about. Mostly wasted energy as few details most probably matters.
Mats
And sorry if my words seem a bit ungracious. It's really not anything personal.