It seems that when selecting the "Day Off" option during a slaves training, it often puts the slave into a permanent "Rest" mode. You can assign their icon to occupy whatever task you want to put them on, but their task status is permanently stuck on "Rest" unless you reload to a save prior to the training session. I haven't done thorough testing to determine the exact cause of the issue, but I have reloaded several times and tried with a few different characters, and found that it has something to do with the "Day Off" training option. After experimenting a little, it appears that it may be related to the work tasks bug posted by Misc Wendall. I can sometimes get them out of it, and sometimes their image is stuck on the task that I previously had them working on.

My machine specs are :

Processor AMD Ryzen 9 7900X 12-Core Processor               4.70 GHz

Installed RAM 128 GB (127 GB usable)

System type 64-bit operating system, x64-based processor

NVIDEA GeForce RTX 3090 Ti

Game Ready Driver - 572.52

Edition Windows 11 Pro

Version 24H2