Re: problem with beagle
How many do you want him to run with? If he's got Tank in his background he is coming from an outstanding line...
At 5 YOA you might have to live with what you've got...Try having him on lead while others are running.
Continued exposure to pack may work but some are so independent from solo work most of their lives they will not hark in and just go about their own business, even quitting a trail when others hark in.
Good luck with him and welcome