@dan I have the same issue after updating Mango to the core v3.7.7
Chrome version is 92.0.4515.131 (Official Build) (64-bit)
When I switch to the old interface and switch to the Datasources tab, the list of data sources does not appear, just the empty white space. The data point tab works well. In the new interface, everything is alright.
When checking the browser's console I found there a bunch of errors like this ones:
Note: The actual IP address is removed and changed with <IP_address> tag.
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/layout/TabController.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/layout/StackController.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/Menu.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/DropDownMenu.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/_MenuBase.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/_KeyNavContainer.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/_KeyNavMixin.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/MenuItem.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/layout/ScrollingTabController.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/PopupMenuItem.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/_WidgetsInTemplateMixin.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/CheckedMenuItem.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE
DevTools failed to load source map: Could not load content for http://<IP_address>/resources/dijit/MenuSeparator.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE