This might happen because your query is too complex. Google might be able to understand word-for-word what you said, but the text package it sends to us will be difficult to process. If we cannot determine a clear intent, then we cannot provide you with the right information.
For example, if you ask Tell me what the top trending stories in commodities from the last twenty minutes are and oh also tell me about the president and what he/she is doing today, you won't get an accurate response. Try to simplify your phrasing and only include one idea at a time.
If you need a complex idea to be processed, we recommend using our Search Tab, on desktop or on mobile, or adding complex queries to your watchlists and then simply asking Google Home to provide you with stories from the watchlist.