On your scanner display 3rd line from bottom, do you see 853.775 or NFM? If NFM, you may be suffering from simulcast distortion and the scanner is not detecting the control channel. Try turning on the attenuator, pointing the antenna various directions, and walking around the house with the scanner. I have ARC-XT also. If you attach your programming file, I will check it for problems.
Try going to the Scanner tab, Communications Setup, and AutoDetect Scanner. I created a file for the York Co trunked system. Save the attached zipped file to your computer and extract. Open the extracted file with ARC-XT and Upload to Scanner. You can delete the old file from the scanner.
The trunked system (York Co SC Trunk) has a system quick key of 1. You can create a second conventional system for the conventional frequencies in York County and name it York Co SC Conv Give it a system quick key of 2. Under System Settings, give it a Hold Time of 1 second. Both the trunked and conventional systems will appear on the scanner screen for about the same time when scanning. Please let me know if you have any questions about programming the conventional frequencies.