Personal feeds presumably can save any item from RSS Ground private feeds and from most of the other public feeds. However, public feeds can be invalid, have bugs and errors in the source code, or miss important parameters. Unfortunately, we don't have control over it and can't process items from such feeds.

In case we can't add an item to your personal feed, you will see an error message:

Another way around - add this item manually. Create a new item in your personal feed and copy/paste content from the needed item.