Expandrive is a program that lets you mount external connections (SSH servers, Google Drive etc.) as volumes on a Mac, so you can drag/drop/save/load as if they were local.
Both the old version I had (6.4.7) and the newest release of version 7 essentially won’t connect to anything at all for me – either servers I run myself or Google Drive/Dropbox (in the case of the last two they get stuck in an infinite loop.)
This is on Mac running macOS Mojave 10.14.6.
There are log files, but they weren’t massively useful.
Didn’t get far with their live support. Similar complaints on Trustpilot. I believe it’s quite a small team (though more than one). Their apps are still actively developed, but if one doesn’t work and they can’t help you…
I asked if they operated a test server, which would be useful for diagnosing problems as they could use it to check the logs at their end. But they don’t.
Possibly the thing to get instead if you really need it is Transmit ($45), though I have gone back to moving files via the command line.