Two posts on the stream forums, one made by me about this pretty horrible bug I just have happen to me.
 

 

My post - http://steamcommunity.com/app/291650/discussions/0/618457398968788348/?tscn=1427570093

 

Other post - http://steamcommunity.com/app/291650/discussions/0/618457398968788430/

After dismissing all my companions and chatting with them in the keep, I grouped them back up and headed out. Three autosave later I need to open my inventory.... every item in each companions inventory is missing, even their quick slot items.

Each person was carrying certain things....
Every potion on Durance.
Every unique weapon on Eder.
Every scroll on Mother.
Every neck and ring on Sagani.
Every food and armour on Hiravias.
(Not -every- but ones I switched to for certain enemies etc.) (All their quick slot items are also gone.)

The other guy had exactly the same thing happen... but caught it in time. I've got no way to get anything back and im 30 hours deep.

I've filled each empty spot with tears.

Just a guess: did you check chests in rooms in Brighthollow?

My characters lost all the stuff they had in their inventory when I dismissed them in the village inn. I already  have got the stronghold but I built only the main hall or whatever it is called, so stronghold inn is unavailable atm.

Just a guess: did you check chests in rooms in Brighthollow?

Every chest is empty along with the keep chest.

Same here:

http://forums.obsidian.net/topic/72673-bug-party-members-inventory-gone-after-switching-them/

This just happened to me, too. I can't tell when exactly, but apparently it is across multiple saves and I didn't notice right away. I'm too far ahead now to backtrack that many hours... ._.;