Good morning, I have started seeing an error last week, last week this was with a test account and this week with my main development account. The error is as follows:
"Error when trying to retrieve data from the network: Engineering Helpdesk failed: The response is not in a JSON format."
Last week, the test account was showing the error on a different SharePoint site being used to develop a new app, this week it is my main dev account that was used to build the app and has owner permissions on the site and app.
I have checked forums and all the solutions I have seen are either not applicable or have not worked. This is not on all apps either so very confusing why its isolated to only 2 (so far!)

Any help appreciated!
Thanks
Mike