P: Ability to sync Lightroom Classic keywords with the Lightroom Ecosystem

That makes the break even worse - keywording is one of the things I really like to be able to do in Lightroom CC as is searching for images with a certain keyword to present them or select among similar images. For serious editing Lightroom CC is all but useless on mobile devices like an iPad for me...

Karl, you might be thinking of somewhat different special case: When a photo in LR Classic is first synced with LR CC, any keywords previously assigned in LR Classic get copied into LR CC, provided that the keywords had been written into the file's metadata (using the LR Classic command Metadata > Save Metadata To File or the option Catalog Settings > Automatically Write Changes Into XMP).

But in general, once a photo has been initially synced between LR CC and LR Classic, any subsequent changes to keywords in LR CC don't get synced to LR Classic, and vice versa.

No, keywords which are added in Lightroom CC to photos imported in Lightroom CC do not sync back to Lightroom Classic either.

Hi John,

I think you need to differentiate between files that are imported into Lightroom CC and then keyworded - those keywords do sync back AFAIK, keywords added in Lightroom CC to files from synchronized Lightroom Classic CC collections though do not propagate either way...

As mentioned in the original topic, Adobe has indicated there were will be no more feature enhancements to sync with LR Classic, so in particular, they have no plans to sync keywords. But if enough people complain, maybe they'll change their mind before the next ice age.

However, comments do normally sync between LR CC and LR Classic, so something specific to your configuration is going wrong. I suggest posting a new thread in the user-to-user forum to get it sorted out: 
https://forums.adobe.com/community/lightroom/lightroom-classic-cc/content

I need my clients to be able to add Comments and have the keywords they add in Lightroom CC computer version to sync with the hosted Lightroom Classic Catalog. 

Sync is not the only critical missing feature. But case sensitive keyword is useless. List of keyword in CC should be implemented. Add keyword in multiple photos in iOS should be a  etc etc

Please, Adobe, implement keyword sync between Classic and Mobile: this is a critical feature for searching and selecting images in Mobile. Sensei search is great, but it cannot cover abstract keywords that describe all sorts of non-visual aspects in images.

Disappointing. Totally non intuitive thinking! You would expect everything added in Mobile would sync to Lightroom CC and vice-versa. Otherwise...what's the point?

keywords created in LR Classic do NOT sync with Lightroom CC