Unable to put items on lvl 1 brand

I just played a game trying to stack my lvl 1 brand, all the items kept on popping off. I tried:

1. using the item components
2. using full items
3. brand on the hex
4. brand off the hex
5. brand on the bench

Am I just dumb?? I've never had an issue with items like this before. I was too tilted to test the items on other units. Excuse the shitty phone video.