Ever since patch 3.17, the editor wrought with bugs when trying to upload custom assets. Here is a picture of the error message I am receiving. I recieve this sporadically when I try to save whilst using custom assets on the Mac editor.
https://i.imgur.com/23desYR.png And here is a link to the page of the assets I am trying to load. On this page I've been trying to load the Tal'darim Assets just fine. https://www.sc2mapster.com/projects/protoss-texture-variations Nothing has changed with the Tal'darim Assets themselves and I've also tried downloading new ones and uploading those with the same result. These assets were working just fine before 3.17. How to replicate: Try to import those same models. Not just a few, but a large group of them into the editor and save a few times. You will likely get the same error message.
I just tested this on the PC editor and none of these errors happened with all the same models loaded. My suspicion is that this might be a bug with the editor itself. As of right now, the Mac editor is not even working.