Syncing between LR on mac and LR mobile for ipad

I have this issue almost every time i do a gallery.

I am a full time weddding photographer, I generally end up with 2000ish images from each shoot and setup the collection in Lr on my mac and syncing smart previews to the cloud so i can download and cull and edit on my ipad.

Pretty much everytime i cull all not all my flagged images show up back on the mac, i can usually fix this by rebuilding sync data it is a hassle but this time it happened that not all the images on the mac showed up in the catalogue when i downloaded them onto my ipad, i deleted them on my ipad and now the synced data wont show up at all.

i would really love to make this my workflow moving forward but every single time i have issues.