Apparently, in rescuing the Moth Priest, he may have hit me inadvertently which made Serana go ballistic. Now the priest has included me in his list of unfriendly folks.

I tried using the console command to add him to the allies faction but every time I return to Fort Dawnguard he attacks me which draws Serana and everyone else into the fray,

I now have Serana wait outside the fort and enter alone. If I see the priest first I cast pacify on him and go about my business. If I take too long the spell wears off and he starts fighting again.

Anyone else have this happen? Did you manage to resolve the issue?

Yep, awhile back, I did have that problem, Isran wooped up on the blind fool, I find it quite amusing that he wears a blindfold and yet can walk around, I think he put the blindfold up a little so he could see