There is a tabbed layout in which when the screen is loaded in review harness, the section is not getting loaded for the first time. In clipboard the page structure is there. But when we refresh data is displayed.
Is it affecting all tabs, or only some? If only some, try to isolate and narrow down specifically what elements cause the issue by either removing pieces one by one until it works or from the other direction, wipe everything out and start with a "hello world", and slowly add your pieces back until it breaks again.
Also does defer load make any difference, or is it being used here?