same thing happenned to my 2019 traverse, first a few weeks after buying it and then again after 6 months..Got in the vehicle this morning and noticed the rear sunroof shade was open and the locking piece that it was mounted to was on the floor. I have been looking and looking all over and cant find this piece online anywhere or even what its actually called. I've attached a photo below, but this piece is what is actually supposed to keep the sunroof shade closed. I'm trying to avoid having to go to a dealership and have this foxed, but would rather order the part. If anyone out there can help, I'd appreciate it.
Thanks for posting this. My wife's 2018 did the same thing a couple of weeks ago. I ordered the 3D printed part. I do have a Chevy part number for the kit to replace the part but it is on national backorder.I have the same problem on my 2020. I've got a 3D printer and some CAD software so I just made the part rather than look for it online. Here are some pic of the two parts side by side.
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The forum doesn't allow the file extension for the model so I can't post it here. Instead, I've posted a link to it to Thingiverse.
If you don't have a printer, you can order if from a number of places, I personally like Shapeways. I've created a link to the part here.
Hope this helps!