Hi all,
New to this forum, although I've been lurking around for a while. I've found solutions to previous problems/errors, but now I've stumbled upon an error which I can't find an answer for - and I'm hoping for your help.
What happens is when I try to add a marketing list to a campaign activity, I get "Invalid Argument":


Any suggestions? 9.1.0014.0017 on-prem.
Thanks!
A.