It looks like all of the Api Keys are using groups
If you want to just get a list of the groups
Have you tried the "Try it out!" button after you expand the groups section?
This will give you the URL's I mentioned above.
I am guessing you have this document?
Also I cant get the API Key textbox at the top of the page to do anything either.
This gave me the same response as before. I did use the "Try it out!" button but even that give me an empty table.
After you click the Try it out! button, is the Response Body box empty?
If you take the Request URL and paste it into the browser URL do you see the same empty page?
Check the log file for the RESTApi in this location:
C:\Program Files (x86)\HEAT Software\RESTApi\log\HEAT.RESTAPIHost.RESTAPIHost.exe.log
Do you see any errors? Is the showing the correct port?
Have you tried to browse directly to the api URL? Is this page also blank?
It looks like the log hasn't updated in months and I see no errors in it.
I would suggest opening a Technical Support case to troubleshoot this issue further.