My apologies, I honestly wasn’t sure I’d get a response so didn’t check back until now. Thanks for your reply.
It was either Friday, Saturday or Sunday. I can’t remember which day. It was a quick login just to refresh base, but I am pretty sure the thralls were present during that ~10 minutes in the evening. I didn’t think they decayed normally though if my base was still up, unless now the thrall decay timer is less than the base decay.