iCloud not working on 16" MacBook Pro 10.15.4 OS

iCloud not working on 16" MacBook Pro 10.15.4 OS. All of a sudden about a week or so ago No photos on my Mac (lost almost 8000 photos off my Mac), photos are fine on my iPad and iPhone just disappeared from my Mac, Mail not always syncing, iMessages not always syncing, other issues happening that appear to be connected to iCloud, as iCloud should sync all of these

Thanks Eric for your reply, I wish there was something new that worked.

But regarding your suggestions, Yes to all of the above and numerous other actions to try to resolve this. Actually, Apple only suggested manually loading photos from iOS into my Mac, but that still doesn't solve the problem that I concluded was iCloud issues. But after doing numerous actions, there is still no resolution. One thing I hadn't mentioned was that my contacts are also not syncing. So I make a change in iOS, but it never syncs on my MacBook Pro, even though I have all settings to ensure syncing. Added note on May 28: Today I updated to 10.15.5.