Have you checked that the feeds you are trying to add are all active and available?
Have you noticed whether you’re getting the feeds from the WordPress Development Blog or Other WordPress News in your Dashboard?
Actually we aren’t receiving those!
In that case, I think it’s a server issue. Your hosts may be restricting incoming feeds. Try contacting them for assistance and pointing them at this thread, if it helps.
They have come back with:
“Please ask your wordpress support if the RSS feeds needs a root access?
Because currently your package is a shared hosting package which does
not have a root access and has some limitations.”
…
I have just re-installed the wordpress. It now takes the first RSS widget – but will not accept or save any more…
The first RSS fee on the dashboard now has data – but not the second.