Sorry that Lightroom Classic is not syncing correctly as 1 file in the Sync status seems to be stuck in the syncing process.
Would you mind sharing the version of Lightroom Classic along with your computer's OS you're working with?
Please checkout the steps below:
Go tohttps://lightroom.adobe.comand review the Sync Errors/Issues Album (upper right). Any unresolved syncs will show up as black thumbnails and have text instructions inside that tell you how to resolved the sync.
After all sync is resolved in Lightroom Web, launch Lightroom Classic and allow it to absorb the changes you've made. If your syncing count hasn't changed in 60 minutes proceed to next step.
Go to Lightroom Classic > Preferences>Lightroom Sync | Sync Activity and allow the dialog 30 seconds to refresh. Leave this dialog in place until all Uploading/Downloading/Pending Photo counts stop changing. Scroll down the list and find the stuck asset and remove it from your All Synced Photos collection. Allow time for sync to reestablish. Repeat if necessary. If the numbers do not move you can try the nuclear option.
In the location where your catalog is stored is a file called 'sync.lrdata'. Close Lightroom and rename sync.lrdata to sync.old. Restart Lightroom. Allow it to sync. If you have a large number of assets, this can take some time. I usually recommend doing this before you go to bed in case it is a several hour operation.