Hi,
just updated from 2023.1.8 to 2023.1.9.
After update, some of our imported FBX models have more vertices in their meshes than before. It’s just a few, but it breaks our pipeline, as we store meta information about vertices, which don’t match anymore. Have not checked if the order also changed.
Never had such an issue, project was successfully migrated from 2019 → 2020 → 2023.1 without issues before.
Hi! Could you please report a bug (Unity QA: Building quality with passion) with your project attached, and paste the issue number here? It would be easier for us to investigate and track the issue. Thank you!
project is 300GB 
I can send you a fbx to test / compare, if you tell me where to send it to.
Is it possible to create a project that only includes a fbx asset that have the issue? Please refer to Unity QA: Building quality with passion for information regarding where to upload the attachments.
i can do that if I find time. Getting a bit tired of reporting bugs, as I have now 7 accepted bug reports on my list, where as none got fixed so far (some are 6 month old already)
Apologies for that (sincerely).
The FBX SDK is a super complex beast with tons of different versions, with every DCC version exporting its data in a different way. Unity itself is then moving along - adding features - in tandem.
It’s a surprisingly complex area of code under the hood.
Bugs allow us to triage/prioritize issues in a central location, including the source assets. I completely appreciate we’re not always fixing them at a fast-enough rate. We’re all devs too, and honestly - we hear you.