Server API tool not remembering my API Key or Secret

[craigja]

This was working, until an hour or so ago!  But now for some reason, when I add my API Key and API Secret to the API_1_3 it does not remember them and if I try to run the tool, I get an Authorization Error.  When I open the tool, I can see the API Key and Secret are both empty, in fact, I dont even need to run it, if I enter values, the click out and back into the tool, the fields are empty.  Im pulling my hair out here!  I have no idea whats going on, can anybody shed any light on this?

Server API (1) AuthorizationError: HTTP error: 400 Client Error: Bad Request for url: http://xxxxxx/webapi/oauth2/token

[craigja · Accepted solution]

Fixed!  Remembered I have changed a DCM seting today - so in User Settings, General, I set DCM Mode back to DCM Optional and its now working again