If you look at this page:
Rowan County, Kentucky (KY) Scanner Frequencies and Radio Frequency Reference you'll note that the main dispatch frequency for Rowan County is encrypted (E). So the only two "clear" frequencies are probably used occasionally.
Then looking at this page:
FCC Callsign WQBQ394 (MOREHEAD, CITY OF) you'll see there are three sites associated with the PD frequencies. While I do not know for sure, I suspect they may be simulcast. That means all three sites are transmitting at the same time.
The 996 line of scanners are lousy at decoding these multiple "barrages" of transmissions. They are either garbled or choppy as you describe. You can check your manual to see if there are P25 level adjustments and do some experimenting to see which is the better setting. But don't expect perfection. A Yagi antenna is supposed to help, but not cure, the issue.
If it was me, I would NOT program this as a One Frequency Trunk system, even though you could. This is shown as a conventional system. I've done this with KSP frequencies and found there is little to gain and the cost is a delay in reception. I think the scanner needs a millisecond or two to get decoding.