New player, I've been captured twice now, both time NPC seems to have taken majority of my items are after escaping and defeating them back (on the normal combat floor that I've been captured in, not prison floor), I saw no sign of where my confiscated went. In both time I've lost wizard's starting arcane tome item, and debug menu doesn't seem to be able to add it back (searching item name provided no results). Is there a way to find the confiscated items back? Or are they just lost? Thanks in advance!

You can recover a part of confiscated items in the chest after advanced 1  floor

This behavior can be tweaked when starting a new game (Loot recovery option)

Also the debug menu is case sensitive
try to type ArcaneTome

then press Add to inventory

should be able to get you 1 book 

If you didn't enable the item recovery option at the start of this save file, those items are unfortunately permanently lost. Also, even with recovery enabled, failing to open that specific crate in the transition layer will still cause permanent loss.

Ah I see, the item recovery setting. Also in hindsight item name is case sensitive should have been obvious. Thanks a lot!