Just an update to this, the weather.srly.io URL and boardclock.com both gave me unable to load issues, but once I removed them and left google slides or other URLs, the issue did not happen.
This issue has been linked to the uzbl browser and how it loads URLs, I have not tested experimental or development versions of screenly yet to see how this will affect your assets/URLs, but I know that the experimental version of screenly now uses something called Qt WebView instead to display web contents so if you want you can try that version if possible… I hear good things about it… remember to backup your assets… unless you can just simply add them then no need to backup, but always good idea to back up, I just know sometimes after a backup + restore, you might run into tiny glitches so you need to re-run the upgrade script and it’s just easier in my opinion to start clean with new assets database if at all possible…
https://doc.qt.io/qt-5.9/qtwebview-index.html