The very many sync related discussions here prompted me to suggest:
Use the Lr Web for adding/moving/deleting Folders or Albums and/or adding, moving or deleting photos within them.
Using the Web version you are working on the cloud side of the sync circle thus the sync process only has to be a down (to your device and desktop) process.
Of course addressing catalog desires can be addressed on a device and/or desktop but the sync then is a bi-directional operation.
On the Lr Desktop version: If you suspect a sync blockage hold Alt then click on the cloud icon (upper right). The window will be blank if sync is complete. If not, items still not completely synced will show there. To establish normal view click a Folder, Album or All Photos (upper left).
If you suspect a sync problem while using the Lr Mobile version, tap the Cloud Icon then Pause Syncing. Wait a few seconds then tap Resume Syncing.
Syncing takes bandwidth and server power. We now live in the world of 12 to 20+ megapixel images and HD video. UHD (4k) video is fast becoming standard. 8k is just over the horizon. Using Adobe Premiere Pro now has an HEVC h.265 8K export option. I tried it with a still image (44KB) as content for a video. A 6 sec clip with no animation/movement ended up being a 14.2 MB file with a resolution of 7680x4320 (almost 34 megapixels). Imagine when we have to sync that size of files.