This is the same problem I had, but mine is in the Notes section for individuals (see Unable to paste in Notes with v. 8.0.4 -- 'Unexpected error' - and how to revert to 8.0.1?). I’ve submitted a support ticket for the issue, and you might consider doing the same; maybe if they get several tickets they’ll look into it.
I suspect that my problem might have something to do with the active URLs I paste into my notes linking individual facts to the corresponding FamilySearch records, but really not sure. I’m getting by using CTL-SHIFT-V to paste, but I really hope the developers can fix this.