I'm sorry, but your question is far from clear. You talk about 'presets' all the time, but I get the feeling that you mean 'profiles'. You talk about a 'LR CC Desktop Catalog', which I assume is a Lightroom Classic CC catalog. Lightroom Classic will not upload custom profiles however, you will have to do this by importing them in Lightroom CC for the desktop. You then talk about 'Lightroom Mobile', but you mention 'browsers'. Lightroom Mobile is the (old) name we still use for Lightroom CC on iOS or Android, so there's no browser involved. Do you mean you are having the problem in Lightroom Web?
I've tried everything and can't seem to find an answer. I'm trying to sync a LR CC Desktop Catalogue with LR mobile. All the photos synced over. But they do not have our custom preset on them. I loaded the custom presets into LR CC and I can see they exist in LR Mobile - but they are not previewing correctly unless I go to edit each photo in LR Mobile and the preset is applied. I need to use Mobile for corrections with my internal team, but if they can't see what I'm seeing in LR CC Desktop this wont work.
Also, the presets are not always the same, so I need to transfer all metadata to LR Mobile, not just specific presets. I've build smart previews and I thought that would transfer so the color was correct. This is not a browser issue - it looks the same on all browsers.
All and all, I just want all the data from each individual file in LR CC Desktop to preview on LR Mobile the way I see it. Is this possible? Seems like LR Mobile is futile if it cannot preview correctly.
First what exact version of LR are you using on your desktop/notebook computer? LR Classic CC V 7.x (The Traditional version/style of LR) or the New Cloud Centric LR CC? Two totally different versions.
We need to know that first
With LR Classic CC V 7.x you do not Sync the catalog with LR Web and LR CC Mobile. You sync one or more Collections with the Web and mobile version of LR.