For some reason I cannot retrieve fields from Marketo. I have attached two screenshots, one showing my config and the other showing the disabled "Retrieve from Marketo" button.
I get no errors or warnings on-screen, and no errors whatsoever in watchdog, nor in my server's logs. This site is hosted on Acquia Cloud, and this is a dev site. Could it be that I need to enable this dev domain in my Marketo account settings or something?
My Marketo module config;

('ADVANCED INITIALIZATION PARAMETERS' is not being used; all those fields are left empty)
The disabled button;

Comments
Comment #2
caspervoogt commentedComment #3
jeffwpetersen commentedHaving this issue as well.
Comment #4
caspervoogt commentedChanged status to Major since this module is unusable in its current state, at least for myself and jeffwpetersen.
Comment #5
caspervoogt commentedSo it looks like the reason the button is disabled is that it cannot connect to the Marketo API. I checked the code and found line 337 of src/Form/MarketoMASettings.php to be the source of the issue;
'#disabled' => !$this->service->apiClientCanConnect(),I do not have access to this Marketo account directly; all I have are its API credentials, so I don't know if there is a setting some place in the Marketo account UI where (maybe) I need to whitelist my dev domain. Maybe someone can explain?
Comment #6
caspervoogt commentedFor me the root issue was that I was using PHP 7.2 and needed the patch from https://www.drupal.org/project/marketo_ma/issues/3085587 .
Comment #7
neclimdulNot being able to connect might also have to do with the API key not being set. Can't tell from the screen shot but the UI for setting this up isn't always obvious.
Think this is fixed though so closing.
Note: you might want to blur your keys next time.