I am having this exact same issue. I use a mini Mac running Mojave 10.14.3 and there are NO green check marks on the files that have been synced. The files all show up to date.
On my iMac that I use at home to work on these exact files, the file sync gets about halfway done...will flash "all files are up to date" and then restart the whole sync process again. (This machine shows green check marks, red triangles, etc.) But the directory that I have synced at home are missing a TON of files (mostly indesign files). I have called customer support and they call back when I am at work instead of on my work computer at home.
I have read through these forums and have deleted the "CoreSync" folders and restarted, etc. to no avail.