Sorry to hear that this happened to you. Don’t know if it’ll help, but it’s “dispel evil and good” that gets rid of the frightened status, not “protection from evil and good.” I actually had something similar happen to me on balanced mode. Lae’zel got hit with fear in that same battle. The battle did end, but Lae’zel was perpetually stuck in fear, and it didn’t run out like it normally does. So I did have to use “dispel evil and good” on her. I’ve had multiple issues with fear being cast on my party. Also had it exploring the Shadow Cursed lands where Astarion got hit with it, and then I could no longer control him. The battle did end in that case as well. But I had to hit him with thunderwave and resurrect him to be able to control him again. Sounds like there’s an issue with the fear spell.