Covid I think has had an impact in this area ... If someone doesn't get back to you in 24 hours ... call again.
I've found that I needed to call even before this ... especially if I had a question which was not easily answered..
I suspect if the email can't be answered by the person who opened it ... it gets put aside. If that is what's happening then it's it seems there is a high probability it's gonna get buried in the queue. What ever is going on it should be corrected as every email should get answered ... even if it's just to say who they forwarded it to or politely inform someone if something is being done or not.