Can't upload document - error #18

Hi,

I can't upload any document new or old to Indesign at the moment.  

Getting error code #18

Have tried various documents that have previously worked on two computers, tried two networks, have checked network proxies, signed out of indesign / adobe cloud and signed back in, restarted computer, restarted routers. 

Running Indesign 15.1.3 on Mac High Sierra 10.13.6 (desktop) and Catalina (laptop).

Have got this code:

{"_links":{"self":{"href":"https://cc-api-cp.adobe.io/api/v2/limits","type":"application/hal+json"}},"small_file_upload_limit":52428800,"rendition_size_limit":2048,"copy_job_subtasks_limit":1000}

Urgent help appreciated. 

Thanks.