I keep getting an unresponsive script error either while searching for photos, or when I try to download.
A script on this page may be busy, or it may have stopped responding. You can stop the script now, open the script in the debugger, or let the script continue.
Did you try over any different browser or try resetting the browser and then check?
You may also refer Stock Troubleshooting FAQ: How do I troubleshoot issues with Stock images?
Hope that helps!
FFJETPACK is a module from Mozilla used in making add-ons for the Firefox browser.
In this thread below it was identified that the Dashlane (password manager) add-on in Firefox was causing the unresponsive issue and that the solution was to disable the add-on.
I was experiencing this issue as well. I usually encountered the issue when viewing the search result page in Adobe Stock. I found that when I disabled just the Dashlane add-on it was sufficient to make the unresponsive alert stop happening.