LR Classic not uploading images from iPhone, ex Hard Drive, Desktop, and unable to sync images

First, this is not a question about LR Mobile. LR Classic on my mac (14.1 operating system) is not uploading images from my iphone. I get only random images, out of order, and only a few. I have checked Full Access in Settings and LR Classic is checked, so I don't think that's the problem. I got a msg to sync catalog, which I did but sync never finishes. Eventualy got another message: "Sync download location is not accessible." I don't know how to correct that. Another message: "LR cannot write to the following directories. Until this problem is resolved syncing from LR may not function correctly." There's an option to Show in Finder, which takes me to Users, but I don't know what to do then.  I just tried to import from Desktop, Pictures and external HD, but they're also a no go. They had been but all my tinkering with this issue changed that too. Many many thanks for your help. LGracey