Lightroom CC does not synch all items from Classic

I’m still looking at the switch from Classic to CC, or at least integrating CC for work in the field, but there is a pretty significant bug in how it syncs collections.  

I have tried a couple of different ways, but if I synch a collection from Classic to CC there is no guarantee that all the images will show up in CC, and it varies which ones show up and which ones do not.

For example, a collection with 355 images that was synched from Classic to CC shows up in CC with 251 images.  I created a new collection with the same images and got 341 images. I have been on a chat with Adobe support about it, and they said they were going to “escalate” to a more senior tech support and I would hear within 24 hours about it. That was more than a week ago. No answer to my questions via email.

I’d like to get this resolved as right now CC is just not compatible with a professional workflow.