This error has been brought up several times before, however this context is unique. I am aware that the following error:
'Error occurred in deployment step 'Install app for SharePoint': Sideloading of apps is not enabled on this site'
is usually shown when trying to deploy a SharePoint add-in to a non-development site. Strangely, I now receive this error message while deploying to a development site, a site I have used to debug apps for months. Does anyone know what might have changed to make this error appear, or where I can check the site type from the site settings?