Not all flags on Lightroom on iPad gets synced to the Lightroom Classic on desktop

[FotoGrundtvig]

I usually cull images via my iPad using Lightroom and edit the images on my computer via Lightroom Classic. 

This has worked perfectly until my last wedding job. 

It seems like not all the flags i make on Lightroom on the iPad is syned to Lightroom Classic.

Last time it was around 300 images that did not sync over. 

I tried "Rebuild Sync data" last time and it solved my problem. 

However the problem has occured again with my current wedding job, and its driving me crazy. 

Rebuilding Sync data every time i need to select some images on my iPad seems like a very impractical solution. 

Any input would be highliy appriciated. 

I have a fully updated version og Lightroom Classic (MacOS) and a fully updated version of Lightroom on my iPad pro. 

[cmgap]

Is it just flags that are not syncing? Not the best answer but can you use a star rating? For example (2) stars for a pick and  (1) star for a keep? When I test this all my flags are syncing. What OS are you running? Are you seeing interruptions in internet connectivity?