How can I force iCloud on Windows to update all my pictures?

I had a huge photo library on my PC (Windows 11 pro) so I installed iCloud (15.2.157) and copied all my files in the iCloud Photos folder. Many pictures were uploaded (I have a lot) but not all of them. I noticed that some subfolders had been ignored by iCloud, so I tried removing them and pasting the contents in the root iCloud Photos folder. It worked to some extent but it seems some pictures are still missing. Right now here is my situation : - my windows iCloud Photos folder contains 17.740 items (16.879 pictures and 861 videos) all in the root folder (50gb) - according to my iCloud client (and iCloud.com), my library contains 12.723 pictures and 356 videos for a total of 37.1gb I tried rebooting my PC to no avail. If I add some new pictures to this iCloud photos folder they get uploaded just fine. It seems I have 5.000 pictures in the limbo. They are not lost, but I'd really like to push them to my online library. What else could I try? Is there a way to force a resync? should I remove all my pictures (eg copy them to another folder on my PC) and then paste them back?