Yep. Same here. I have uninstalled OCD, rebooted, re-installed and also specified Full Sync. And, if I upload, then try to upload again after a few minutes I get:

<| Date: Sat, 14 Dec 2019 22:45:12 GMT
<| Server: Apache/2.2.15 (CentOS)
<| X-Powered-By: PHP/5.6.40
<| Cache-control: no-cache
<| Content-Length: 206
<| Keep-Alive: timeout=15, max=100
<| Connection: Keep-Alive
<| Content-Type: text/xml; charset=UTF-8
<|
<| <?xml version="1.0" encoding="UTF-8" ?>
<| <Envelope>
<| <Error>
<| <Code>506</Code>
<| <Description>506 Another upload is still in progress. Wait several minutes and try again</Description>
<| </Error>
<| </Envelope