What was the error/ response you were getting with unsuccessful scrapes? My guess if it was 'Queued' for a very long time is that it was a rate limit issue - we set the limit according to Zenrows documentation to throttle the number of results sent over to them. We can't do much about this unless they raise the limit on their side.
If it was timing out, it might have been due to the fact that Zenrows sometimes needs to re-run the same request a couple of times to succeed. Let me know if this is what you were running into and if it’s something that comes up often and we can look into how to handle this better. Let me know if it was something else and I can look into this more!