Files opens as Untitled

[paul.millet]

hello adam,
follow these instructions :

Thumbnails not showing on .skp it show on .skb

hello, this sometimes happens if you installed another version of sketchup that you then uninstalled. right click on any .skp file and chose properties. in the “open with” line, click modify and pick anything else than sketchup, for example notepad, and apply then close. do it once more and set it back to sketchup in the suggestions, thumbnails should be back

your problem is the same than unappearing thumbnails.
for some reason, even if sketchup is selected as default program to open with, you have to break the link and relink