Mark Seam Breaks Existing UVs

At work, I’m editing an order of contractor assets. Every model comes in with UVs and textures, but it’s my job to make sure they’re up to a certain standard before integration. While doing one edit in particular, I marked a seam with the intention of using it only to simplify my selection process (Select Linked w/ Limit by Seams).

However, when I added the seam, the UVs seemed to auto-unwrap. I wasn’t broken up about it at the time because it wasn’t imperative that I mark seams, but I thought that it was very strange. Now I can’t add seams to any mesh, in progress or finished, without the UVs distorting.

I’ve never seen this before, and I’m hoping that it’s just some option I turned on and not a major bug. Does anyone have any ideas?

Look in Toolshelf under Mesh Options, ensure you don’t have ‘Live Unwrap’ enabled


That was it. Thank you very much, Richard. For whatever reason, I looked over it and thought it was associated with the “Live Unwrap” used with pinning.