The only time I see this is when I forget that I have to target twice to revivify. After hundreds of hours of play, I STILL forget that I have to target the body, then target clear ground. I usually click the body, then nothing happens, so I click the body again, and I get the blocked message.
Or click the character icon, then try clicking it again. Same message.
Also, I thought you could go to camp after a character died and then you could talk to Withers for a resurrection, even if the character wasn't travelling to camp with you, no?