I'm using a presumably up-to-date everything here. Trying to just grab a web page w/ some papers, discussions, etc about some research relative to my interests™.

https://www.cl.cam.ac.uk/research/rainbow/projects/hdr-csf/

I get a 'way stylized folder looking' icon in the connector button. I click it, I get the usual save box with proper / selected folder, etc. but with a "An error occurred while saving this item. See Troubleshooting Translator Issues for more information."

Looking at debug output when I try doesn't give any obvious errors- versions are a little confusing, being different depending on where they are in the output:

the HTTP responses are:
zotero(5)(+0000001): HTTP/1.0 200 OK
...
X-Zotero-Version: 5.0.87-beta.3+6d2e843f5
X-Zotero-Connector-API-Version: 2
...

But the POSTs are
...
X-Zotero-Version: 5.0.64
...

Not sure if that matters, but
as in-
zotero(5)(+0000236): POST /connector/getSelectedCollection HTTP/1.1
Host: 127.0.0.1:23119
Content-Type: application/json
X-Zotero-Version: 5.0.64
Accept-Encoding: gzip, deflate
Connection: keep-alive
Accept: */*
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.2 Safari/605.1.15
Content-Length: 2
Accept-Language: en-us
X-Zotero-Connector-API-Version: 2