Can't connect to the account "Facebook" in Systems preferences

Hi all, I'm using High Sierra (10.13.4) and I haven't been able to get my MBP to sign into Facebook even though I know the password is correct. I keep getting an error message as above every time I try. I've searched for solutions and found on older MacOS versions that removing and re adding seemed to work for some people but I tried that and it doesn't for me. Any other ideas?

BG