I'm on Stadia if that matters.
This wasn't happening to me until the most recent patch. Up until then, the trade wasn't exactly normal, but it was something I could deal with as a player. Every time I clicked on an object to trade, for instance, that object's icon stayed in my inventory throughout the rest of the trade with a "0" at the bottom indicating that I didn't have any more of that object.
Then I would conclude the trade after clicking over all the items I wanted to get rid of and the zeroed out icons in my inventory would disappear.
So different than it was in the earlier patches, but something I could work with.
Now, after I click on one item, and sometimes even before, my inventory shows as completely blank. I have to click on the "all" icon to get the items to come back so I can continue selling.
I already felt like the trade system was difficult to work with. This obviously makes it way more difficult.